We did it! Inspired by this Mashable series, and using this tutorial, I built a little rig for spinning burning steel wool today, then took it out to the local park with Amy and Miles after dinner. Amy shot the images while Miles and I took turns spinning. Not nearly as scary as I thought it would be, but we still wore a protective hoodie and goggles, and brought along a gallon of water just in case (none of it needed).
These are all 30-second exposures. The hardest part is getting the distance right – tough to know in advance how far away the subject needs to be, so the tops/sides of several of these are off. More practice needed. Would also like to figure out how to change the color of the sparks. Any chemists in the house?