ACTUAL GAMES/DEMOS: www.mofunzone.com - Click Game Downloads to get lots of free game demos to try.
www.boomtown.net - Sign up for free, and get access to LOTS and LOTS of the latest game demos and more!
www.gamespot.com - Same as above. Gamespot is my favorite game demo site. On the downloads from here, I sometimes get up to 300kb/sec or over! GREAT SITE.