I bought a half dozen GCN games last year, and two controllers. I don't play them very much, but I think I got all 6 for about $60, so it was worth it.
Viewtiful Joe 1&2 - the first one is the better of the two.
Metroid Prime 1&2 - meh; GCN controller for FPS is baaaaad IMO. Good games though if you can stand fighting the controls.
Killer 7 - good game from NMH creator; totally different game though
Ikaruga - crazy arcade shooting type game
[MEDIA]http://www.youtube.com/watch?v=EGNSdcy-apU[/MEDIA]
Gameplay from Ikaruga