Living in a college town means there are a lot of people moving several times a year. And this means boxes of stuff left on the sidewalk on a regular basis.
I usually check these out, when I have the chance. I've gotten lots of books that way, a lamp, and, last night, a spare computer keyboard. I haven't tested it yet; in the worst case, I'll end up dropping it at the Alameda County Computer Resource Center for recycling if it doesn't work.
A lot of trash in this world would be an amazingly useful thing in a different time or place or for a different person. When a chance to scavenge comes up, give it a shot.