I'll give this one a go - obviously deliberate motion blur from the West Chester Twilight Criterion race yesterday. It was a great day for waching a race, perfect weather and quite a competition.
This is from the elite women's race:
Taken with the K10D, FA*85/1.4, f/7.1, 1/13th second. Click the image for a slightly bigger version.
The blur, in this instance, is caused by the wind rippling the surface of the water in a storm water pool alongside a freeway. The result is a blurred reflection that required only a light breeze - no panning, no slow shutter speed and no moving objects.
Here's one of my first attempts at long exposure in a crowded room at night ... no tripod used ... although i did use the top of an entertainment unit to hold the camera (should have learnt how to use Mirror lock-up though as it did move slightly when the exposure was taken.
Picture could have been sharper really ... but moderately pleased for a beginner (can only get better really.)
Here is another sample. It's an experiment that failed as it didn't come out at all the way I had planned it to do. Everything was wrong, from the weather to my mood. Anyway: