Top Gun: Combat Zones. That game looked kind of fun, but WOW. I was wrong.
Viewtiful Joe. Not so much a regret, but this game is not that good. I still haven't finished it, after 2 years.
Super Monkey Ball. Right up there with Viewtiful Joe. It's just not that good.

I totally hated the FLUDD mechanic (I think that was the name of the water thing), and the camera annoyed me. The camera I could have lived with, but the water thing just seemed to ruin it for me.

hey, the water was fun

Not for me.

I completely agree about the camera, but I loved FLUDD! You must hate Mario's B and down move in Brawl

Shadow the Hedgehog, Cel Damage, Donkey Konga (preordered, ouch), Super Bubble Pop, Geist (Nintendo broke this one), P.N.03, Enter The Matrix, and Space Raiders are just a few of the games I've bought that left a sour taste in my mouth after playing o_o

Mario Party 4, 5, 6, 7 (8). I didn't buy all of them (some my brothers got) but, Jesus Christ, what was I thinking?

Disney's Party...ugh
I would've said Shadow the Hedgehog and Super Monkey Ball but if it werent for those game I wouldn't be able to trade them for a PSP. Best deal I've made:)

Simpsons hit and run. I played it at my cousin's house, and I thought it'd be good to get, but I never ended up playing it much. That seems to happen with games I've played before and buy myself.

Eternal Darkness. What the hell was all that hype about?

Shadow the Hedgehog. Meh platforming, not enough speed, weapons made it boring and too easy.

Really? I enjoyed that game. To me the weapons made it harder, I just liked the homing attack better.

Smash N' Drive- Bought it used, but its still terrible game.
Rayman 3- Terribly childish and its nowhere near as good as the second one.

maybe you´ll call me crazy, but Mario Party 7, its fun in the beginning but then its really boring

None. I have played practically every major console released since the 2600 except the 'cube. Not at a retail kiosk or friend's house. Not even via my Wii. No particular reason it was the only Nintendo console I never purchased, I even had a Virtual Boy.

Mario Party 4. I bought it after enjoying the DS version (in my pre-Wii days), which my daughters and I played together quite a bit. But Mario Party 4 was incredibly tedious with poor minigames. The minigames on the DS version are so much better. I'm not eager to get another console Mario Party--especially as the slow pace of the gameplay seems magnified on the television screen.

Viewtiful Joe. I was expecting so much more. I know reviewers liked it because it was stylish, but I quickly grew disenchanted with it. I think I prefer my brawlers to keep it simple, including at least one mode where I can just button-mash to let off some steam.

Wave Race, Super Mario Sunshine as I hated the whole fludd mechanic and Delfino so I gave the game to my niece so I guess it was not a total waste. I am sure there is a few others.

Super Mario Sunshine is awful, but Rampage: Total Destruction is the one game I regret buying. I won't throw it away though, because I like my collection to grow, not shrink.

Mario Party 7 and Pokemon XD Gale of Darkness.