Any Grateful Dead.
Early Black Sabbath
Pink Floyd (especially 60's). Wish You Were Here, Dark Side of the Moon
Planet Gong (very trippy).
Isao Tomita - The Planets (classical album done in synthesizers -- triiippppyy).
Velvet Underground.
Early Stones (60's)
Doors - esp. American Prayer
Hendrix
Very Early Judas Priest (Sad Wings of Destiny, Rock-A-Rolla)
Hawkwind (made for tripping)
Jefferson Airplane
Spirit - Future Games (A Magical Kahvana Dream) (((highly recommended - if you can find it - if not leave your e-mail and I'll work something out with you)))