Last night being the 4th of July, I tried shooting fireworks for the first time, and some of the results are below. I started out with my 14-24mm lens, but found quickly that this was way too wide for the view I had, so I moved to the 50mm (75mm equivalent on the D7000 sensor), and this worked nicely. All of the shots below are at that focal length. Not all the bursts end up nicely centered in the frame, or in the frame at all, but I took enough shots that I could weed out the crap and be left with some nice ones.
I operated the camera in bulb mode, which means the shutter stayed open as long as I depressed the shutter release, which in all cases is for many seconds. I found that the duration of the shutter release was not important to the exposure; rather this controlled how many different explosions are overlaid into the same shot. So I could open the shutter while the sky was black, wait until I had a few good bursts, and then let the shutter close.
The explosions themselves are quite bright, and using an aperture of f/10 or so resulted in plenty of depth of field focused at infinity, as well as plenty of light for a good exposure, even at ISO 100.
Of course with long exposures like these, a tripod is a must, as well as a remote shutter release, so as not to disturb the camera and cause motion blur.
The other comment I would make is that I was not sure where exactly the fireworks were going to appear in the sky, and I located myself in a less than ideal spot. On the other hand, I found that having some trees or other foreground framing actually improved the shots. Next year, I am going to go out earlier and try to get to a place where I can put some people in the foreground.