One of my favorite subjects for long exposure night time photography is the Ferris wheel. While the wheel is moving, the colors are often changing and its quite hard to choose the right moment to start the exposure. It's like a game, sitting with the camera in your hand and waiting for the best moment to shoot... and then, when you look at the results, you are either thrilled or disappointed...
Here's a photo I took on a freezing night in Yokohama, with the giant Cosmo Clock 21 Ferris wheel, which I wanted to photograph colored in blue (my favorite color)...
Ferris wheel Cosmo Clock 21, Minato Mirai 21, Yokohama EXIF info:
Nikon D90
Lens: VR 18-55mm F/3.5-5.6G
Focal Length: 26mm
Aperture: F/7.1
Shutter Speed: 1.6s
ISO Sensitivity: ISO 200