Personally I think it's a rip off to trade games or get rid of them unless you're getting a close to equal value of what you paid for it. I'd suggest trying to find some odd jobs to do, babysitting, mowing the lawn, that kind of thing. I'm not one for getting rid of games I've purchased.
If you absolutely must though I'd say get rid of the gamecube games. You don't need melee, you won't play it after brawl comes out. For wii games, definitely keep mario galaxy. I'd say get rid of one of the other three wii games, again, only if you absolutely must. You have a month before brawl comes out, you can find some work to make money before then. Personally I'd get rid of Zelda or Metroid before Resident evil.