I can't recommend anything other than Wavebird for a wireless controller. I think you can even buy a white Japanese one so it matches your Wii.
As far as good Gamecube games, I didn't see anyone mention Soul Calibur II. Link. In a real fighting game.
From the games listed above, these ones are awesome and well worth playing:
Get the Wii version (not GameCube) for these games:
I haven't played these games, so can't really comment:
Here are some games that I recommend, and weren't mentioned already:
Finally, here are some games that you might consider, but aren't for everyone:
The link below has some interesting reading about GameCube games worth checking out:http://www.racketboy.com/retro/2007/04/best-undiscovered-nintendo-gamecube-games.html
Seconded on pretty much everything above, especially the Wavebird.
Metroid Prime is getting a compilation on thw Wii soon, all 3 games on 1 disc, all with wiimote controller support. http://en.wikipedia.org/wiki/Metroid_Prime_Trilogy
If you've never played MP, the best decription of it is also what I consider a compliment of the highest order: It's technically an FPS with metroidvania elements, but it PLAYS like a Metroid game that just happens to be in 3-D.
All excellent too:
Viewtiful Joe
Beyond Good & Evil
Paper Mario
Skies of Arcadia
Thanks for the numerous responses! I think I'll get myself a Wavebird and a memory card and get ahold of Wind Waker and Tales of Symphonia.
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Legend of Zelda: Twilight Princess
Eternal Darkness
Tales of Symphonia
RE4
Killer7
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I really enjoyed:
Baten Kaitos
Any of the Zelda games
Mega Man X Collection
Mega Man X Command Mission
Pikmin 1 and 2
Tales of Symphonia ( one of my favorite RPGs ever)
Some other good game are Star Fox Adventure and Mario Sunshine, and Star Wars Rogue Squadron II: Rogue Leader.
BBaur77: ... Star Wars Rogue Squadron II: Rogue Leader.
... Star Wars Rogue Squadron II: Rogue Leader.
This is a very good Star Wars game that everyone seem to have forgotten about. Possibly the best Star Wars flying game available... feels like you're watching the movies. Great suggestion!
Baten Kaitos is good, but not great. I'm close to the end (probably a few hours left, judging from how long I've been playing the second disc). Although I have mostly enjoyed my time with the game, it's not something that I would recommend to everyone.
Legend of Zelda: Twilight Princess is better on Wii, although if you can get the GameCube version cheap then it's not a big difference.
ejamer: BBaur77: ... Star Wars Rogue Squadron II: Rogue Leader. This is a very good Star Wars game that everyone seem to have forgotten about. Possibly the best Star Wars flying game available... feels like you're watching the movies. Great suggestion!
There's also a Star Wars Rogue Squadron III too, is it better than II? Which is the better one to get if I only pick one?
mhatter106: There's also a Star Wars Rogue Squadron III too, is it better than II? Which is the better one to get if I only pick one?
The general concensus seems to be that Rogue Squadron 2 is better because (a) it covers most of the biggest and most exciting battles you expect to see from Star Wars, and (b) Rogue Squadron 3 has a bunch of poorly made "on foot" missions. However, if you own Rogue Squadron 3 then you can play all of the missions from the second game as co-op missions... which is pretty sweet if you have a (local) friend willing to play along.
So for single-player get Rogue Squadron 2. For multiplayer, get Rogue Squadron 3.
(Disclaimer: I own part 3 right now, but have 2 in my request queue because I think the single player mode is more useful/important.)