I like stuff made from old technology. I have coasters, keychains, and a business card holder made with old motherboard in my office.
There are lots of things you can make if you have the skill and material to do it. I would love to find this stuff in a cache.
that site has some cool stuff
there is also a cacher around here who folds origami and leaves it in caches. they also have a puzzle cache where you have to fold a pagoda in order to get the coordinates
I make 'recycled circuit-board' keychains. I basically demolish old electronic devices, and cut up their circuit boards, drill them, and put a keyring through them. I don't trade them for anything...just leave them in caches