Sites? I don't have any links saved, but type in "motorcycle ice racing" into Google and you'll get tons of results. There are hundreds of small and large groups, clubs, and ice racing series' all around the world. There's Speedway, ice road racing, motocross/motard type roadracing/oval racing, sidecar, etc., etc.. There's also different types of tires. Some guys use BIG, long, spikes (Speedway), or you can have a screw head type stud, plus variations of the two.
I belong to a small regional club but we are sanctioned by the CMRC and it's rules. Some of our riders go and participate in the national level races. The CMRC sanctions what is probably the biggest ice racing series in North America. Pacal Picotte is a regular participant. We run on a smallish oval (under a 1/2 mile, usually bigger then a 1/4 mile...we run a few different tracks) on motorcross bikes. Mostly CR/KX500s, and big thumpers (YZ426,CRF450,XR650).