Neopets
Offers a variety of virtual pets to care for, as well as games, contests, communities, and combat simulations.
http://www.neopets.com/

Play Free Arcade Games
Comprehensive online game collection with no signup process or complicated steps to get started...just a simple way to play games online for free! Action, adventure, arcade, sports, and much more.
http://www.excessively.net/

Play free games
Unleash your gaming skill with this collection of free to play online flash games, pick a game and start playing from the huge collection of arcade, skill, puzzle, racing, shooting and action games.
http://www.afkf.com/games/

Myspace Games
Free Games for MySpace, Xanga, Friendster profile, blogs etc. 2300+ Free Online Myspace Games to play, all selected for their quality.
http://redpython.com