My 2.5 year-old loves Gcompris and just about all the flash-based games on pbskids.org. He's got enough coordination that Pingus keeps him quite entertained too. Though not quite games, he also loves Stellarium and Celestia too. Pull that old beater box out of the boneyard & drop a copy of edubuntu on it. Now my kid knows more about navigating a linux desktop than his mom does. :-)