Tons of good recommendations here, I did'nt expect to get so much feedback. Well so far I added Iron Butterfly's In-a-gadda-da-vida to the list, a couple of songs from the group Egg and also I added a Steve Hillage track. I found a really cool group from Germany that put out a few albums in the 70's, they're called Dzyan. In particular they made an album called Electric Silence, it's mainly instrumental but really good stuff. Then I found a few old LPs by a group called Soft Machine, I guess they're more jazz than rock but they have some really trippy songs. I managed to find a couple of old Pink Floyd albums at the same record store, I have Meddle, UmmaGumma and Wish You Were Here. Finally I also found a couple of records by a group called King Crimson and Can, really good prog rock stuff. So sometime this week I'll try to record all of those albums into mp3 format.
Used record stores are great