Cannon fuse
One of the things I played around with last weekend was waterproof cannon fuse. This stuff burns at the controlled rate of 30 seconds per foot and will even burn underwater. I did not try lighting it with sparks but I suspect it could be done. The fuse has a tendency to jump around a bit as it burns if it left loose but winding it around small kindling works well. If you wrap it too close to itself it will ignite itself at these close spots, speeding up the burn time.

Small, waterproof, hot.
Gee, sounds like my wife!

-Blast