Post some good freeware games!

I'll start with Chalk

"Sporting chalk-like visuals, this great looking arcade style shooter includes an innovative approach to its controls: draw chalk lines to destroy enemies against the backdrop of a blackboard. The lines to draw will depend on the type of enemy at hand. Some enemies require you to draw a line connecting all green spots, others require a line connecting ship and the bullet it fires. A quick tutorial is available from the main menu that gets you acquainted with all the various techniques. Definitely not your average shooter and it's a lot of fun to play. It's another exceptional game by veteran developer, Joakim Sandberg."

http://www.konjak.org/chalk.htm

Just another japanese shmup
http://www2.tky.3web.ne.jp/~yosshin/my_works/index.html

ANOTHER Japanese shmup, but you can make your own super bosses and such.
http://mokeron.hp.infoseek.co.jp/zg/fraxy_main.html

Make my own bosses? That sounds pretty cool

Words That Follow (aka WTF).  It's a little different than the other responses.  It's a multiplayer picture captioning game.  It's broken up into rounds.  You're shown a picture and everybody has about 45 seconds to caption it.  Then everyone votes on the best caption, with points awarded accordingly.  You just need to find a good time when a bunch of people are playing.

It's pretty addictive.

http://www.side-quest.com/sqgames/

cave story
the amerikan cave story clone
akuji the demond