ultrasports are cheap and good if you don't want to wear out your nice race tires on bad road surfaces. they don't feel very fast, and they are heavy, but IMO they handle well and are fairly flat-resistant. certainly better than some of the other cheap tires out there (low end kenda, cst, etc).

the maxxis detonator that was mentioned is a good alternative. faster ride, better handling than the ultrasports, but also less durable IMO.