NAPALM, freeware that lets you draw over your Windows desktop, using animated fire ink, and tweak the fire generator parameters.
Allows saving/restoring of artwork & style and import of bitmap files. It is useless, thus absolutely necessary ;-) OK, maybe you can use it to leave notes on your desktop!
Requires Windows XP, Vista or above (will NOT work under Windows 9x). Download 1,4 Mbytes.