Ikaruga is good, but be prepared to rip your hair out. I've played it, and it's probably the hardest game out there. Only five levels, but each will take you forever to beat, except maybe the first couple, which will take nearly familiar.
Super Monkey Ball is great. It's also very hard, and quite a lot of fun in single player. The second is better for multiplayer, but it's too easy single player-wise. People don't seem to understand how great this game is...it's one of the best arcade puzzle games I've played in recent memory.