One for the Brits; it's a site that buys phones off you. They give you pretty good deals as well, 36 pounds for my Nokia 6300, which only cost me about twice that a year or two ago. I'm selling another very old phone for another 3.50 so I'll get about 40 quid back for things that would have otherwise just sat in my drawer.
http://www.fonebank.com/
http://www.fonebank.com/