Go to Netcraft - Search Web by Domain Just enter the offending domain name and you'll get the Netblock, which will be a link to the host or the host's data center.

I've had the same issue in the past when a web host ripped off my tags to get better search engine positioning. I don't know if it worked, but I complained to google. Since that time, we've dropped markedly from the engines. Used to rank Number One for the search term "web hosting" in the late '90's in a few major engines including Excite, which was the google of its day I suppose.

Good luck tracking the ungracious host. We never hesitated to pull infringing sites off our network.