Both Baltimore and Washington are now experimenting with "rubberized" sidewalks. Made out of recycled tires, the material promises to be more durable over time than conventional asphalt or concrete. Unfortunately it's a lot more expensive, so only time (and testing) will tell if, in the long run, it's actually cheaper than the more conventional stuff. Considering that it seems to take 15 guys three weeks to fix most sidewalks around here, if the stuff actually works it doesn't seem to me it will take all that long to break even.
Via Daffodil Lane.