iPhone: Have a lot of junk sitting around your house? Boxes is an app that will help you organise all that junk and sell it if you want to.
At its core, Boxes 2 is a simple way to track all your junk, whether it's books, movies, games, or whatever else. You can scan an items UPC or take a picture. From there, you can then sell those items from within the app, follow other sellers, and more. The social network aspect makes it easy to sell stuff if you don't feel like messing around with eBay, though you obviously won't have as many eyes on your stuff. Either way, you don't actually have to sell your stuff if you don't want to.