Gov't Mule is awesome. I have a bunch of their live stuff which is so much better than their studio recordings. I was so bummed that I missed them play out here last week. They were in a little club (~800 people tops) but I was out of town travelling for my job. Sometimes work really sucks.

Other than Mule I also also listen to these bands a lot when I'm stoned:
Grateful Dead
Allman Brothers
Hendrix
Led Zeppelin
Pink Floyd
Black Sabbath