Obscure...well since I'm not familiar with what other Floyd fans have, I can't say whether the things I have are considered obscure, but here goes...

-BBC sessions from '70 & '71
-original unmastered recording of DSOTM
-the 18-disc compilation A Tree Full Of Secrets
-Interstellar Encore
-Syd Barret - The Madcap Laughs
-Granny Takes A Trip
-the live set from Smoking Blues
-the Zabriskie Point Sessions sndtk

I included only the really hard to find live sets that I have. I have quite a few other live performances. Also, I didn't think OBC was really all that rare --- I have that as well.