How about some netradio. Don't have to worry about changing discs. I recommend Somafm.com - their "Groove Salad" channel. Also, "Digitally Imported" from shoutcast.com is nice.
In my opinion the best rolling music is Naw-t-boy Ecstasy Vol. 1, 2, and 3 and Naw-T-Boy afterhours 1,2,3 and 4 its mix of hard trance and progressive house very trippy and makes you roll good.
Here's some artists I like to listen to anytime, E just makes it better
The Mars Volta
Sparta
Thursday
At The Drive In
Artifakt
Astrix
Dark Nebula
Saiko Pod
Psytelligence
Bush Martians In Wonderland
Bamboo Forest
Atomic Pulse
Nightwish
Opeth
Tool
A Perfect Circle
Pretty much all of them are crazy Psy-trance mixed with drum and bass and hardcore jungle, Tool and A Perfect Circle...well if you don't know already i feel sorry for you. Opeth is, well...it's hard to explain, resembles soft death metal if you can believe that, Nightwish is operatic metal, sparta, thursday and at the drive in are in a class all their own, kind of like emo with some twists thrown in. The Mars Volta is some trippy shit, i like to listen to it on hallucinogens Will list more for you guys when I'm home on my own computer.
non-techno songs that are awesome while rollin:
Mr. E's Beautiful Blues by the Eels
Clocks by Coldplay
LOTS of Nine Inch Nails
and i listened to Motorcycle Drive-by by Third Eye Blind w/ a good friend and had like the most emotional, happy moment of recent memories:D
I'm a big Kottonmouth Kings fan. I've listened to KMK while smoking almost everytime I smoked for the last 4 years. The first time I heard their cd Rollin Stoned was while I was rolling, I thought it was the best cd I had ever heard. Tangerine Sky and Positive Vibes are great songs to listen to while rolling.
KMK is really good but that oakenfold cd is insane espically this one song feeling weird it has this part 3 minutes into the song That is insanly trippy u gotta hear it to understand