Team 1097 has used treads since the forming of our team. Our origional treads were from a snowblower donated to us from Tahoe Sports and Motor. This year we used this website listed somewhere in the chiefdelphi discussion above:
http://www.robotcombat.com/store_tanktreads.html They were basically modified forms of snowblower treads that you could buy seperately from the snowblower. We then machined some of the parts down for use on our bot. We ran out of time to machine the cogs, which would have been nice, since they were expensive. Just to give you an alternate option to Breco, which can be expensive. I think this entire year we were pushed once, maybe twice, and the treads have always been a major benefit for defensive strategies.