I still rue the day I traded my trusty Zenith in for a new Canon A1 (that's a dig at the trade in, not the superb A1). It was years before I could afford another, and made sure it didn't want to eat expensive camera batteries, but then never went back to the subject.
I played in B&W and colour night photography for a while, but the arrival of the battery operated camera killed it as I was going really low light and half an hour was becoming a short exposure. B&W always won out as colour film misbehaves with these long exposures, and if you're anywhere near streetlights, everything picks up the colour cast from them.
One weird effect you will find if you go in for really long exposures in B&W is that the pic will begin to look like a daylight shot as light scatter gives a white sky, rather than black. Needless to say this also needs a scene selected without light sources in it.
For a bit of variation, and one that will work with digitals that don't have very long timed exposures, try light painting. One method is to set the camera up as usual, open the shutter and then use a hand held manual flashgun and use repeated flashes to cover the area of the subject. Carefully executed, this can produce perfect pics of items way outside the normal guide number of a single flash shot.
Enjoy