Christopher Palmer at Recursive Irony found a company called Cordova and Sons, in Cuba, New Mexico, which recycles used tires into building material. Not an entirely new idea, but one worth keeping in mind for your next construction project. It turns out that tires used in buildings can cut road sounds five times better than any other standard building material, and has a heat insulation value of R-240. The article (scroll down) about Cordova and Sons, in the High Country News, also links to an index of tire and rubber recyclers around the world.
What if your tire-insulated house catches fire? Nasty!
The Earthship folks have been doing this for a while now, using the tires more or less as is, so it's closer to reuse than recycling. http://www.earthship.org/
In the streets of Chennai (aka Madras, India) i've seen piles of people working on used tires, i think doing something to make them useable again as tires.