I listen to all kinds of shit.

Chemical Brothers (any techno/trace brings a trippy vibe to the room)
Crystal Method
Aphex Twin
Fatboy Slim
DJ Tiesto
Primal Scream

Blur (Just trippy bands to listen to...great talent and chill songs to just chill to :P)
Gorillaz
Fugazi
Cake
OPM
Tool
APC

Rancid (Upbeat music...always fucking cool to listen to)
Against Me!
At the Drive-In
The Clash
Bear vs. Shark

Bone Thugs (Rap....the best of the genre, as far as I'm concerned)
BLESTeNATION
The Roots
OutKast
RZA
Wu-Tang, in general

Radiohead (Usually make sure this type of music is playing when I'm smoking with some girlies...I like listening to it all, though. :P)
Postal Service
Death Cab
Sonic Youth
Pixies
The Cure
The Beatles

Sublime (Stoner classics)
Slightly Stoopid

I can't leave out O.A.R....more of a get drunk and chill kind of music, though.