If I had a car, I would be the most addicted kind of dumpster diver imaginable. Sometimes I almost weep at the sight of all kinds of things and perfectly usable building materials just thrown away yet, alas, untransportable by me and my trusty bicycle.
Sometimes garbage is even good enough to warrant a headline in the New York Times. Here's a piece about one spectacular dumpser find.
A more realistic sample of what happens to you when you get enamoured by other people's junk here.