+1 for:
Metroid Prime 3: Corruption
House of the Dead: Overkill
Wario Land: Shake It!
Samba de Amigo*
Boom Blox
Pinball Hall of Fame: The Williams Collection
Animal Crossing: City Folk
Excite Truck
Geometry Wars: Galaxies
Super Paper Mario
Super Monkey Ball: Banana Blitz
SEGA Superstars Tennis
Sam & Max - Season One
*Samba de Amigo actually rocks--seems like tons of reviewers were used to the Dreamcast controls, tried to control it the same, and were disappointed when it didn't work. But I can handle it decently, and I had a small party last night with some friends over and one girl who never played it before picked up the controllers and worked her way through a bit and kept bumping the difficulty up--after 1/2 hour, she was getting 95% on HARD difficulty! Clearly they work well, you just need to push the Dreamcast controls out of your mind. Amazing party game, too...