Some of the best are:
"Black House" in Brazil- Nogeuira brothers, Anderson Silva among others.
Greg Jackson's in Alberquerque, NM- Jon Jones, Jardine, GSP.
Tristar Gym in Montreal, Canada- GSP.
Grudge Training center is getting a lot of hype these days. It's in Denver, Colorado. - Marquardt, Evans, Carwin.
Extreme Couture in Las Vegas, Nevada.- Couture, Forrest Griffin, Stephan Bonnar.
Fun trivia: In danish "kamp" means "match" or "fight". So Martin Kampmann really lives up to his name.