I made a keychain out of an old INtel 386 DX processor.
1) Use a pair of snips to remove all the pins except for 10 or 15 on one corner of the cpu. Only cut those in half. You will use them to connect your chain/ring.
2) Break out your soldering iron and slab some solder on the corner of the cpu you only cut the pins in half. The solder will stick to the pins.
3) Put some solder on the ring or chain you want on the cpu.
4) Solder the ring or chain to the cpu.
I also whipped up a batch of epoxy and dipped the cpu in that. It made for a very good shock barrier and kept the CPU clean.
A friend of mine drilled a hole in my Pentium MMX during wood shop so I could make it a keychain. I didn't bother with removing or cutting the pins, so I bent them over so I wouldn't get stabbed in the thigh.