My Xbox 360 is only a fairly new addition to my electronic family. Thus, my collection of games is pretty skimpy. Aside from
Rock Band,
Rock Band 2 and
BioShock, everything else in my collection I'd borrowed from my brother.
On the other side of the spectrum, I had a wide variety of Wii games. Most of them I beat long ago, never to be played again. Of course, there are a few mainstays in the collection that will never leave, namely
Super Mario Galaxy and
The Legend of Zelda: Twilight Princess.
Perhaps the greatest thing to happen to my video game collection is
Swaptree.

Here's how it works: you pick a bunch of stuff that you want. Then you list a bunch of stuff that you're willing to get rid of. Finally, the website will lead you to trade directly (or through a three-way trade) with someone who has what you want. The only cost is a couple dollars for shipping.
Here are some examples of my recent trades:
1)
WarioWare: Smooth Moves for
Halo 32)
Burnout Paradise for
Sid Meier's Civilization Revolution
3)
Super Paper Mario for
Left 4 Dead
But it doesn't have to work that way. You can trade your copy of "Harry Potter and the Chamber of Secrets" for a used copy of "Larry Potter and His Best Friend Lilly." Perhaps you'll trade your old copy of
Office Space for a used copy of
The Buddy Holly Story.
Swaptree is cheap, effective and addictive. I'm a little worried about running out of stuff.
Oh, and don't try to swap those 30 copies of
Shark Tale you found in a garbage can on 10th Street. Nobody will ever take you up on those. Do you seriously blame them?