I ordered something from Cabelas and included with my order was a pre-postage-paid envelope for an organization called "Cell Phones for Soldiers". Apparently what they do is collect old cell phones via these envelopes, sell the cell phones to a recycling company, and use that money to buy phone-cards for deployed soldiers. (According to their website, it was started by two teenagers!)
Welcome to Cell Phones for Soldiers!
This may be old news, but I had never heard of it, and I plan to donate one of my old cell phones.