Excellent submissions and stories behind them so far.

Mine will fit into the "I've got to try this" category.
I saw a YouTube clip by Evan Sharboneau aka PhotoExtremist and just had to try this technique.

In short it goes like this:
  1. Stuff 0-grade steel wool into some kind of a metal frame (I used a whisk) that you can tie a line to
  2. Start a long exposure shot
  3. Light the steel wool on fire
  4. Let it SPIN!
I think it turned out quite well:
Name:  assignment_34.jpg
Views: 257
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7D + 15-85 @ 21mm, ISO100, f/8.0, 20s

I have a few more in my blog for anyone who is interested.

And please take care that you don't light anything on fire with the sparks and remember to protect your eyes if you give it a try!