sleep, the melvins, high on fire, OM, bad brains, earthless, bongzilla, big business, boris...the list could go on and on.
Sleep, Porcupine Tree, The Velvet Underground, Pink Floyd, Shpongle, Aphex Twin, David Bowie, Brian Eno, Charlie Parker, Mr. Bungle, Sun Kil Moon, Yes, Liquid Tension Experiment, The Gypsy Kings, Parliament Funkadelic.
Marilyn Manson Cradle of Fillth They're great ones for noticing things you've never noticed before in the songs
As far as metal goes, some Stoner Doom. Electric Wizard Sons of Otis Sleep Ufomammut Bongzilla Etc etc
I like everything when I'm high. I even like listening to some rap music. Well, I hate emo music but it makes me laugh when im stoned because the lyrics are so funny.
Any Blotted Science song is pretty kickass. Though I admit that lately I've been listening to Eazy-E.
I have had some great times with getting stoned and listening to black metal. It's not what I listen to most of the time when stoned, but when I'm in the mood for it it's awesome. So obviously I can't pick one band cause it depends on the mood