Gazelle.com is a site that buys old electronics. You go to their site, search for the type of item you're wanting to sell, fill out some information about it (like condition, model, etc.) and the site will tell you right away how much they will pay you for it. If you can't find the item you have, you can e-mail them about it and they'll let you know if they're interested or not. They even pay for shipping. I have to say, they make the entire process very easy on the seller.
The kind of things they're looking for are computers, gaming systems, digital cameras, cell phones, etc.
I recently sent them my old laptop and a Play Station 2. The PS2 was in perfect condition (I'm not much of a gamer, so it didn't get used much). However, the laptop was from 2006 and had been used to death. I'm sure I could have paid someone to fix it up and make it run better, but since it was already 4 years old I decided to just go ahead and buy a new one. So you can imagine my surprise when Gazelle actually e-mailed me to let me know that my laptop was actually worth a little more than they had agreed to pay me! I had already sent them my stuff, so they could have easily just paid me me the amount we had originally agreed on. There was no reason that they HAD to go ahead and pay me more, but they did. How many companies can you think of that are actually that honest?
They paid me $65 for an old laptop (which is great, because it would have cost me a lot more than that to get it fixed) and a PS2 that I only used once or twice. So I have to say that I'm very pleased with Gazelle. If your looking for a place to sell your old electronics, I highly recommend them.