Just got this from the 2BloxDC folks -- there's a charity drive at the fields at 11th and Kenyon (aka the new astroturf field behind Tubman Elementary) where they're accepting used athletic shoes. I have a couple old paid laying around, sounds good to me.
They'll be "used to help build new playgrounds" which I guess means the rubber will be used on the playgrounds. I'm down with that! I hear the good ones will be given to children in Africa, and the rest used for rubber. So, double good.