The Flaming Lips cd, Zaireeka and Yoshumi Battles the pink robot are amazing.
Circulatoy System - check out the song "outside blasts"
I don't recall seeing the 13th floor elevators on here.
Procol Harum
I still think a few of ELOs albums are a little progish. Check out fire on high
You could even make a case for indie rock groups such as Sonic Youth (they have some beasts, like diamond sea or washing machine or sympathy for strawberry) and Radiohead (Kid A and Hail to the Theif) IMO but I don't think they quite fit the prog category, still, indie is just as different as prog. Both groups are also noise rock to some extents, but both groups are very progessive in their sounds.
I know some of these sound ridiclious and it may not sound like i know a lot about prog but i know a lot about this genre and love it...I just felt like tossing a few ideas around, because prog is a very open genre.
**My Soulseek name is "carl the floyd fan", feel free to d/l what you like!