Shooting fireworks doesn't require any special equipment. Most amateur photographers should have everything on this list. Anything that you don't have already is worth picking up, since it will be useful in more situations than just fireworks.
- digital SLR (I use a Canon EOS 5D)
- wide-angle lens (I usually use a Canon EF 17-40mm f/4 L)
- good, sturdy tripod (absolute requirement! Exposures will range from 2-10 seconds)
- shutter cord or remote
- memory cards, memory cards, memory cards
- charged, spare battery
The lens you need really depends on the size of the fireworks display, and how close you are. Often you'll be surprised how wide you need to go, so you should go a little wider than you think you'll need. I always try to be close to water if I can, to catch reflections, which usually requires my widest angle lens, even on my full-frame 5D.