Here is an idea for anyone who doesn't go to school, doesn't work full time and doesn't ask for anything in return:
Next time it's hard rubbish day, go out and collect whatever you see potential in and jazz it up a bit. Whatever it is, it might just need a generous layer of orange paint or a few diamantes (those were some pretty silly suggestions, I'm sure you can do better). Then when you are done, return your new masterpiece to its original home. For bonus points, attach a little card with a story or just a greeting to the owner. I would keep it ambiguous though - to maintain optimal mysteriousness.
And for those who are dismissive of other people's privacy (don't be shy, I'm one of those types) have a secret camcorder set up to film the owner's reaction when they find their revived junk. You would have to be the Grinch to not feel the least bit charmed to receive such a gift.