Not a new game, but certainly on its way to becomming a classic, Super Monkey Ball by Sega was originally released exclusively for Nintendo's Gamecube, and now coming to XBox and PS2 in early 2005. Super Monkey Ball Mini is a Flash version of the same game providing mini levels that take advantage of similar gameplay mechanics as the original. Use the mouse to tilt the floor and guide Aiai—the monkey in the ball—to the goal, the highlighted area on the play field.
This mini version is a great way to get your Super Monkey Ball game on when away from your console.
Update: If you like this, then be sure to check out Super Monkey Ball 2 mini games.