http://lifehacker.com/5803308/amazon-will-now-buy-your-old-electronics-from-you

http://www.amazon.com/Electronics-Trade-In/b?ie=UTF8&node=2226766011

If you have old cell phones, mp3 player, cameras, etc, Amazon will tell you how much they will give and even pay for the shipping. They grade the condition on 3 levels (Like new, Good and Acceptable condition). I have a first generation iPhone 8GB and they are offering $65.25 for "Good" condition. I also put in my current phone (iPhone 3GS 32GB) and they are offering $184 for "Good" condition. I didn't submit it, I just wanted to see what they were offering.

So if you have any old stuff laying around and would like some Amazon.com credit, seems like a pretty good deal to me.

Gazelle.com also does this, but they give you actual cash.