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Im not too familliar with Jethro Tull but some pretty trippy bands i got in my collection (apologies in advance if this gets long, im just gonna look through my itunes and pick out a few at random and i have about 10 solid days worth of music)
Battles ( Very cool, trippy group Ive heard them classified as "Math Rock", check out the album Mirrored, or youtube the vid for "Tonto")
Boards of Canada (very chill downtempo electronica, one of my favorites to listen to when stoned)
The Books (not sure how to describe them but maybe modern folk/electronica/music concrete (tape music)... one of the most interesting live shows ive seen)
Buck 65 (think Tom Waits, if he got into hip-hop)
The Flaming Lips (very psychedelic group, check out the albums Yoshimi Battles The Pink Robots or War with the Mystics
Kid Koala and Bullfrog (check out the album Bullfrog, may be listed as just Bullfrog for the artist too)
Les Claypool's Flying Frog Brigade (check out Purple Onion or Of Whales and Woe)
The Mars Volta (never really been able to get to into them, but a lot of people like them and they're pretty psychedelic and trippy, like a newer pink floyd I guess)
Modest Mouse
Morphine (more people should listen to this band, very cool kinda jazzy stuff)
My Bloody Valentine (tripped out, shoegazer rock)
Presidents of the U.S.A (just plain goofy and fun)
Primus
Radiohead (new album is prety sweet, and it's free from thier website also OK computer, and Hail to the thief are greats)
Soul Coughing (very very underrated band, they got a prety unique sound, check the first 2 albums)
TV On The Radio (interesting sound, not sure how i'd describe it)
not really sure what styles you're into but there's a pretty ecclectic mix of some groups worth looking into
thats a pretty sweet list of bands dude, some of my favorites are on there. Battles is freaking amazing, I didn't know there were others on the forums that liked them. Personally, even though I like their new cd, I think their older ep's were way cooler, in general, all their music is awesome.
I also love the books when I'm high. I get really caught up in their sound. Its really interesting music if you can set aside time to just sit and listen. It's not really music i'd consider bringing with me in the car or something though, all the sounds would probably mess with my head lol.