Like everyone else has said, a breakaway reflective collar is a must because you never know!
If your cat is going outside, like mine do, I would recommend a bell because otherwise you tend to get little 'presents' left on the doorstep and that ain't nice! I have to put a bell on one of mine or she brings home shrews, mice, birds..you name it. The others don't bother catching anything fast. If your cat doesn't go outside, I can't see why you would need a bell.
I would also recommend microchipping your cat. Its dead simple and relatively cheap (in the Uk it is anyway) and it really is peace of mind.