Russ, go play Wrath of Earth and you'll see the raw power of Assembler. :)

I recommend:

Vector Tower Defense

and

Drop Kick

Bars Of Black And White

Nice and slightly disturbing.

Take the concept of Sokoban and wrap it into visuals from Cadaver and you get Grave Shift 1, a nice retro-styled, isometric tile game.

For fans of Transport Tycoon: http://www.freeonlinegames.com/rpg-g...ay-valley.html

http://www.newgrounds.com/portal/view/498969 - Super Mario 63! Basically, it's a 2D version of Super Mario 64, with the FLUDD pack from Sunshine. It also comes with a nice level editor, and you can share and play other people's levels.

http://www.newgrounds.com/portal/view/301341 - The Fancy Pants Adventure! This platformer's a little bit like Sonic, what with its insane speed and such. It focuses more on physics and momentum, though, and it's a lot of fun. The sequel is even better.

I always wanted a game about war trains:
http://www.miniclip.com/games/rails-of-war/en/

This thing is so addictive that it shouldn't be free...
http://www.elementsthegame.com

Take a quick dose of Street Fighter II!
 

Feel the need to play Street Fighter II right this minute?
Can't download the game to your computer?
Want a true arcade feel and not just a wimpy flash remake?

If so, THE DOCTOR IS IN!
AND HE'S GOT THE CURE:
http://www.kongregate.com/games/Game...t-fighter-2-ce

Have a nice day now, and STAY IN SCHOOL!!!

Sorry if I posted too late, but here's a few I'd like to share.

Arcanacra - Fun throwback to vertical shooters, created by one of my favorite japanese freeware developers, KEIM.
http://www.yomogi.sakura.ne.jp/~si/S...ra/v04_e.shtml

Cube Colossus - Different twist, almost arena styled. It also has an actual plot!
http://www.kongregate.com/games/lucidrine/cube-colossus