Adios mentioned it, but I really like El Yucateco. It comes in several different versions, but the green stuff comes in around 9000 on the Scoville scale. They make a habanaero version that is around 11,000 but I can't find it in stores around me. I'm very picky about my hot sauces, they have to be hot but they also have to have good flavor. To give you an idea of how hot the green stuff is Original Tobasco has a rating of around 2-5k (I don't know why the big range). The thing with hot sauces and their heat rating, though, is that you aren't drinking the crap straight, so you could just add more of a weaker sauce and get your dish up to the same spiciness.