Descending Blocks - Base2 / Insync Imaging Inc. presents a Tetris-type game in javascript.
Electric Lighthouse's Hangman - instantaneous action and sound effects, graphic representation, well-chosen words (from easy to difficult), score storage; lights, and all the bells and whistles.
Mike Naylor's Five by Five Poker - get 10 good poker hands in 5 rows and 5 columns and try to make the high score list; javascript capable browser required.
WallBangers - climbing simulator utilizing javascript and computer animation to create an educational and entertaining site for rock rats and non-climbers alike.