A tripod (obviously). Preferably stabilised with a heavy bag to prevent wind sway.
Low ISO negative film preferably (look up reciprocity failure if you really want the gorey details) I use Fuji Reala 100 which is excellent for this as it's a bit green heavy, so the sodium glare doesn't go mad and it really picks up the blues of things like neon. If you're digital, stick it on the lowest ISO.
Under f8 will prevent starburst, over f22 will guarantee them (depending on the nature of your lens these vary slightly). I stick the camera in AP mode and let it work out the exposure (works really well with both Nikon and Contax even at 5min+ exposures despite what the manual says).
A polarising filter can really help (loads of glare and strange light reflections are minimised)
A cable-release or remote control is ideal as this minimises the vibration of pressing the button.
Mirror lock up is supposed to help with vibrations, but I've never bothered because my F3HP body with motordrive is soooo heavy that it isn't going to flinch.
So to summarise, a standard cityscape is great with a wide lens, good tripod, f8-f11ish, low ISO.
Hope this helps and look forward to seeing your results!
Rob