We tried donating recently and the women's shelter said that they used to but the cost of dealing with re-activation, old batteries, sorting out broken phones, wiping memory etc., just wasn't worth it.
I find that duct taping it to a cardboard box with wires sticking out of it and leaving it outside of city hall is a pretty good way of making it someone else's problem to deal with.
Or, bring four of five of them with you to the airport and leave them behind at airport security on your next trip. Make a big deal out of emptying your pockets, then dump out 5 phones and say, "Screw you, you take 'em" and walk off.