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.