Not for the hardcore restoration people out there, but when I had my bicycle recycling program for kids and teenagers, we couldn't use chemicals so we removed surface rust with crumbled aluminum foil. It ultimately left sort of a "brushed" metal finish, but it was very effective. I also thought the brushed look was kind of cool.

For really bad rust, we'd soak the part in store-brand Cola for a few days. You'd be amazed at how much THAT stripped off!

Of course, as others have said, there's no replacing the protective qualities of the original coat of chrome