The Green Habanero hot sauce by El Yucateco. Not a day (or a meal usually) goes by when I don't use this stuff. I have 3-5 bottles in my fridge at all times. Amazing stuff.
Or if you really want to die, this stuff: (
http://www.hotsauceworld.com/357maddoghot.html)
I've had a bottle for 2 months now, and haven't made a dent b/c its too damn hot.