Here's a breakdown of Newgrounds material that I find to either be required viewing or among my personal favorites. If you like a movie/game you see, you can click on the author's name/picture to the left of the screen to check out what else they've done. Alternatively, you can scroll down about halfway down the page to a drop down box and instantly click on a movie or game that they have made. This method is easier if you know the name of what you're looking for.

Also, if you wish to keep up on what I consider great, you can check out my favorites on my user page. There are other methods of finding worthy material on Newgrounds without my help. The front page is a perfect place to catch the latest movies and games that enter the Flash Portal. Speaking of the Flash Portal, the Best of All Time, found on the far right column of the page, contains the best movies and games on Newgrounds, as voted on by the people (you can vote, too!) Another great way to find quality content that may have slipped through the cracks is to look at the Treasure Hunt 2008 page. The fourth and final page has a link to all of the previous pages, but the first page is the easiest to navigate.

And so without further ado, the goods (in no particular order):

Randy Solem is one of the best artists on Newgrounds who animates with video game sprites. He hasn't done much lately, so some of his older stuff may seem a little dated. It's all good, though!
Mario VS. Sonic (VGDC) is a classic battle bewteen two video game rivals pre-Super Smash Bros. Brawl.
Mario The Mack Daddy is a fun little animation of Mario dancing around. The first one is pretty old-looking compared to today's standards, but there are at least three others that are much better and more recent. Watching them will give you the background to a joke in...
Rise of the Mushroom Kingdom: Part 1 is one of my personal favorite series on Newgrounds. It's a masterpiece. Watch all four parts!

TheWeebl is a funny, quirky animator from London.
weebl and bob is a wacky little series. I've found that people will either love it or hate it.
badger ver.1 is an animation that became a viral video on the Web a few years back. I personally don't think it's anything fantastic, but it's nice to know that it originated from Newgrounds.
Magical Trevor is another video that got around the Web. There are three sequels, but I think this one is still the best. It loops, BTW.
On The Moon is a great series if you like funny situations and random occurances. There are quite a few episodes out.

David "Doki" Firth is a fantastic animator on Newgrounds. His Flashes have central themes revolving around the strange, creepy, and metaphorical.
Salad Fingers is a legendary series on Newgrounds. There are quite a few episodes, so if you like this sort of thing, then I highly recommend that you check them all out.
Burnt Face Man is another series by David Firth. It's not as creepy, but more silly. Also worth checking out.
Dog Of Man is one of Mr. Firth's more recent submissions. It's not part of a series, but it's still amazing.

Matt "Krinkels" Jolly is a sick animator! The only main thing he's worked on is the Madness series, but that's more than enough from one person.
Madness is a series about a character names Hank J. Wimbleton who fights his way through endless waves of foes. It's action at its peak!

Proxicide doesn't have much on Newgrounds, but all of it is of excellent quality.
MK vs. SF is a three-part series about certain Mortal Kombat and Street Fighter characters dueling in some of the best fight sequences on Newgrounds. A must-watch, even if you're not that into fighting video games.
Madness: Deus Ex Machina won the Madness Day 2007 contest. It's a combination of Madness' violence and MK vs. SF's style.

TypeQueen is most well known for creating Charlie the Unicorn. He hasn't made a whole lot else, but his other stuff is also worth checking out, too.
Charlie the Unicorn debuted on Newgrounds long before it became a huge viral video on YouTube. It's silly, but funny. Watch the sequel, as well.

Rodrigo "El-Cid" Huerta is another good animator. He recently earned himself a job as an entry level animator for Dreamworks, which is pretty cool.
Mega Man vs. Quick Man is El-Cid's first Newgrounds submission. It's a sweet fight scene of Mega Man fighting one of the bosses.
Mario Kart Underground is a fun mash-up of Mario Kard: Double Dash!! and The Fast and the Furious. I find it very amusing.
Bambee may very well be the best thing El-Cid put out. It's hilarious on every level. It even got El-Cid accepted into his university.

ZombieLincoln often does work for a group called the Clock Crew on Newgrouds. You don't really need to know what the Clock Crew is to understand everything, but it helps.
CorpeGrinder's Dream is an experimental, trippy, and beautiful piece. Definitely worth a look or two.
Short Flash about Bill M. is a wondorous tribut to the one and only Bill Murray. For the love of God, watch this!
A Short Flash about Clams is an animation in the same vein as the one above. What it lacks in Bill Murray, it makes up for in the form of a really surreal experience.

Waldemar "W-P-S" Schuur is great. Think of David Firth's dark and strange style and twist the Hell out of it! This is what you end up with.
MagicalRainbowPedophile1 should be a series and you should watch it.
Anusboy is pretty out there. Watch it in a good mood.
blek koffi is along the same lines as Anusboy, so if you liked that, then you'll love this.

Karri "Catoblepas" Esala animates as if doing acid were common practice. These animations will hypnotize and scare you, but in the good way.
Robot Gets Angry is about a crazy robot and the trouble it gets into.
Bad Baby gets even crazier. You might have to watch it twice to catch everything.
Harry The Harlequin Fetus will probably end up scaring you. Be careful if you're combining it with drugs.

Splapp-me-do is an animator with a funky sense of humor.
Sonic Breaks his Neck is a hilariously disturbing look into the world of Sonic the Hedgehog.
The Impossibe Quiz is impossibe. I dare you to win. I dare you.
Badly Drawn Dawg Series 1 is the first collection of the Badly Drawn Dawg cartoons. If you liked it, then check out the others.

Michael "The-Swain" Swain is a very talented author who is actually close friends with the Newgrounds staff.
Blockhead is a series about a goofy character who is absolutely braindead stupid. The best part is that his conscious is an old grumpy man who can never get through to Blockhead.
Mastermind is another original series by The-Swain. This one revolves around an evil tyrant who is constantly trying to rule the world. Funny stuff.

Fraser "FarFromSubtle" Agar started animating on Newgrounds, but soon moved on to work on a long-running live-action series.
Awesome Video Games is a series of videos in the form of a late 80s/early 90s television show. They talk about old NES games like they're brand new. It's hilarious, especially since shows really were this bad (like the live-action segments of the Super Mario Bros. Super Show).

Egoraptor only started submitting to Newgrounds in 2006, but since then, he's become one of the most popular artists on the site. His "awesome" movies have been some of the most parodied styles in a while.
Awesome is a whole new genre consisting of profanity, crude drawings, and exaggerated mockery. It all started with Metal Gear Awesome, and it all rolled downhill from there.

Adam "chluaid" Phillips is one of the best animators on Newgrounds. This guy is a former Disney artist and won Newgrounds' Movie of the Year 2007 with Waterlollies.
Brackenwood is a storybook fantasy world that Adam created. These Flash movies are of the highest quality.
hitchHiker: part One is a two-part tale based on a true story. Its great visuals combined with its suspenseful mood make this a fantastic Flash.

Oscar "Get-lost" Johansson is best known for making the Castle series. The whole thing is very action-oriented and the quality of the work improves dramatically with each new entry.

Jeff "JohnnyUtah" Bandelin is a very talented artist who actually works for Newgrounds. He's big on cock jokes, which I really appreciate... I'm not gay!
300 QUEERS is a tale of the 300 Spartan warriors who had to fight against the Persians... naked.
TANKMEN is a series based on the iconic "Tankman" character often seen with the Newgrounds logo. It has guns, profanity, and cock jokes.

Chris "Sexual-Lobster" Voight is another very talented artist who creates funny cartoons based around drugs and unlikely situations.
Greasy Moose is his flagship series. Characters such as Gooseman, Manny, Fernando, and Hernando are always finding themselves in crazy adventrures. I don't think I can choose one episode to call my favorite.
Angry Dog is a newer series by Chris. This seven-part series follows the events of a lizard becoming mayor, much to the despite of George.
Space Duck is a surreal journey through a sketchbook.

Edmund "Bluebaby" McMillen is a long-time author whose artistic works in recent years have made him exceptionally popular within the Newgrounds community.
The Bandlands is a series of games set in a dark, twisted world. They're all a lot of fun.
Coil is one of the strangest and most beautiful games I've ever played. It's like a poem set in a dark alter-reality.
Aether is another strange game. This one is less dark than Coil, but is way more wonderous and imaginative.
The C word is a cock joke gone so, so right.

Marc "RomerJR" M. is one of my personal favorite authors on Newgrounds. His animations are hilarious.
Sick Animation is a series of unrelated cartoons covering topics that are more often than not offensively funny.
Hans Dick is a series of related cartoons about Hans and his everyday life. It is authored under Marc M.'s alias, Hans "HansDick" Dick

Pavel "JunkYardAnimations" Lubanski is another artist who focuses much of his efforts on dirty situations and cock jokes. What can I say? I'm a sucker for this kind of stuff (literally).
Behind The Doors is an epic game in which you must escape a hotel that you are trapped in. Hint: smoke a cigar.
Ring Of Fire examines a problem I assume most everybody has at some point or another.
Fuck Mr.Hatcher is another game. This time you must go on a quest to have sex with your best friend's father. Truly a classic.

jerry "Jerryjackson" jackson is a wonderful author who has aspirations of one day working as an animator for Disney. He makes a series of cartoons under his own name, Jerry Jackson.

Celarent is a pretty talented artist. He hasn't contributed a whole lot to Newgrounds, but everything he has is really good.
The People's Mario displays Mario fighting his way through the Mushroom Kingdom in the style of communist propaganda.
Rotten Antenna is an eerie little piece that leaves you in wonderment.
Look up at the sky is an almost hypnotic video to just sit back and watch. It does loop, but you may not want to stop it.
Future is one of my personal favorites on Newgrounds. All of the animation was done in 2D. Wow!

SamBakZa is an excellent artist who has created one of the most notable series on Newgrounds. There she is!!! is a touching five-part story of love and acceptance between a cat and a rabbit. Its animation quality is top-notch.

And now for some personal favorites (also in no particular order):

FDA, an acronym for "Fuck Dat Ass," is a series of cartoons centered around the penetration of the pooper. It's not all gay, but some of the later stuff is, such as the ultimate classic music video Taint of Love.

Will "Stamper" Stamper also works for Newgrounds. He specializes in media design, Street Fighter, and sexual tension. Rebecca is by far the best Flash Stamper has ever created. It may even be one of the greatest Flashes, period. Watch it over and over and over.

Queers of War is a collaboration made by members of the Newgrounds team during a Cartoon Slumber Party. It's a little gay, but totally perfect if you just happen to like Gears of War and dicks.

Rokémon! is a cool Flash by Billy "DragoonFenix15" Cass featuring a Pokémon-type battle between two non-Pokémon characters.

Star Wars Gangsta Rap: SE, by pyropymp, is an original music video chronicling the original Star Wars trilogy in the musical stylings of gangsta rap.

Getting Off The Train, by alienredwolf, is a short story of a man who "arrived" at his stop.

Bad Hair, by Nelson, is perfect for anyone who has had experience smoking the chronic.

It's Still Me is a comeback film by Squeezy "TimFrommeyer". It's deep.

Lost Farts, by Karl "Hereder" Fredriksson, is the epitome of funny. Do not watch if this is your first Newgrounds video. It may be too much.

Night in Hotlanta is a collaborative effort by number of members of the Newgrounds community. This 13 minute long noir film is a little stange, yet funny, yet serious. Definitely worth a look.