I am in the process of playing:

Mario and Luigi: Superstar Saga. I have to collect these Beanstar pieces. Fun mini-games and puzzles though.

Mario Kart: Double Dash!! - I blew through 50cc and 100cc, but have yet to work on 150cc.

Star Wars: Jedi Knight: Jedi Academy - This game is pretty fun. Better than Outcast. I hear it is short though.

Star Wars: Knight of the Old Republic - I enjoy this thoroughly. I stopped playing, but will probably get around to it soon.