One of my favorite finds was an atomic clock... cleaned it up, replaced the batteries, and voila! I had me a nice full-featured clock... not only that, but one of my neighbors must have one too, as the outside temp feature works on it but I never got the transmitter that went with it!
My theory on why in the world someone would throw out a perfectly good clock? They were too stupid to realize that yes, even "atomic" clocks run on batteries...
Tons of lawn equipment and bicycles get tossed for equally ignorant reasons... not that I mind, really. Keeps me busy.