My D70 takes an IR based remote in the place of the cable release. That's how I do "bulb" shots. Press the remote once to open the shutter and use some manual timer (aka. stop watch) and then press it again to shut the shutter when the time has passed. I read somewhere that since its IR based, you could grab any universal TV remote and set it to the proper frequency and use that too. I'm not sure, but I think your D80 might have that "bonus feature" too.

The remote is great for group shots when you want to be in the shot too.