If you were planning on nabbing one of Samsung's newest Galaxy phones, and you have an old device, then you will be pleased to know about today's news. They just started a buyback program in which you can trade in your old smartphone and get some cash value for it. The amount varies depending on the device, but can be upwards of $300 dollars. The program works pretty simply. You just have to provide info on the type of phone you are trading in. Then, buy a new Samsung device and send in your old phone. Samsung will send you a check within 30 days.
That seems like a pretty sweet deal, but in all honesty, you may be able to get more bang for your buck to sell your device on eBay, but if you don't want to be bothered with the eBay hassle then this is a no-brainer.
One other side-note, if we are understanding it correctly, it does look like the program can also work retroactively for some purchases since Samsung only requires you to have your receipt available.
Source: S3Forums via Facebook - Samsung Buyback Program