Creative Shots With Longer Exposures

Dan Heller has some thoughts about longer exposures leading to creative exposures. Slower shutter speeds will obviously blur moving objects, and Heller's article shows some of the creative things you can do with that basic fact as well as introduce a neat piece of equipment-- Neutral Density Filters. Neutral Density Filters allow you reduce the amount of light coming into the camera, without stopping down your aperture.

Update: His tutorial about Fill Flash is also worth reading.