I am a member of Goozex.com, and love it. A lot of people don't know what it is, so I will explain. Goozex.com is a company that allows you to trade used video games through a web application over the internet. What I find so cool about Goozex is their genius business model.
Goozex requires you to buy trade credits for $1 each which are used for each trade. When you trade one of your games you are rewarded with points that you then use on other games. The genius behind it, is all Goozex does is manage the points and trades. Shipping is taken care of by the traders. This puts Goozex at no risk, and since it is based on a points system they can easily guarantee any trade.
For instance, say you request a trade and someone sends you a game and it is lost in the mail. For a rental service like Gamefly, they send the games out, so they are out whatever the worth of the game is. With Goozex, all they have to do is credit everyone their points back and all is well. They can guarantee satisfaction because what they are really trading are non tangible points that can easily be replenished. This is a mind blowing concept to me and I am probably more in love with the idea than I should be, I just wish I thought of it first.