The title of this Wikipedia entry is "List of artificial objects on extra-terrestrial surfaces," but it really could be "Litter Beyond Earth." At least these objects, unlike the ones we've left in space itself, aren't likely to whack into anything or anyone and do major damage, but it does demonstrate that our human tendency to leave crap behind wherever we go doesn't stop inside our atmosphere.
Incidentally, Wikipedia also notes that the only person ever hit by artificial space debris was a woman walking in a field in Tulsa, Oklahoma in 1997. She was hit in the shoulder by a chunk of blackened metal from a Delta rocket that had fallen from space. It had been slowed down enough by atmospheric re-entry that it didn't hurt her significantly. There's a good story!