I live in a good sized apartment complex. I figure it never hurts to at least have a look in both dumpsters. Last Saturday I pulled out a Dell P2 450 and a 17 inch Dell Trinitron monitor. Not the greatest but both work well.
It's also worked for me to run out and ask people when I see them throwing away something good. I've grabbed a gas grill, patio furniture, and another computer by just asking. People tend to throw away perfectly good stuff when they're moving.