Lordrrr hit most of the better games right now.
I'd also suggest Guitar Hero 3 when it comes out (unless you prefer it on another system). Other than that...all of what he said, as well as...
Elebits (it's just basic simple fun)
Red Steel (I'm probably one of the few people that liked this game but oh well...I still say it's fun)
Resident Evil 4 (if you haven't played it on another system it's a great game...if you have played it...it's even better on the Wii)
Mario Party 8 (only if you like mini games)