The Earth Observatory site has an article about nighttime shots of various cities around the world taken from the ISS, as well as some thoughtful commentary on certain features and trends that can be found in the images. They also link to a 126mb quicktime video tour that I highly recommend pulling down and watching.
A while back an astronaut put together a barn door tracker out of spare parts that allowed him to take long-exposure shots and keep the target in the center of the frame while the ISS hurdled through space above it. It's really spare parts, too--he's using an electric drill to turn the knobs!
The picture above is of Tokyo. Its bluish-green color, they say, is indicative of all Japan for their use of mercury vapor lighting. Something else I found interesting (hand-picking from a great many interesting things here) was that some cities bear a striking resemblance to other nasa images, particularly of nebulae found way on the other side of the ISS.