[youtube][/youtube]
In it, they use a piece of pencil lead to create a light. The lead is attached to a car battery, and it glows brightly for 3-4 min. He also mentions to keep the molten lead away from gas.

SO, I was thinking, why not use it as a dirt cheap igniton sorce for spudguns? You could attach a 12v battery to a switch (the trigger). The switch would lead to two screws which would go into the cannon. These two screws would be attached to aligator clips, which would grip 1/4 inch of pencil lead.
You just saved a piezo. Also, I was thinking of using this idea in a combustion cartrage. I was thinking for a pistol style combustion, and each cartrage would contain a peice of lead, propelant, and a projectile.
Any thoughts? Has this been done before?