This performance of Green Onions from Norway circa 1966? shows the roots of prog rock. Also notable for a Steve Cropper Telecaster solo reckoned by some to be his best.
http://www.youtube.com/v/U-7QSMyz5rg&rel=1
Except prog rock was a hideous self-indulgent mess that probably should never have been born. IMHO of course.
The really good stuff that came out of and after the 60s R&B explosion was back in black music: War, Sly and the Family Stone, GSH, Marvin Gaye, Curtis Mayfield...
Back to the OP: hasn't anyone ever head of Jimmy Smith or Jimmy McGriff? Those guys were far better Hammond players than most others. In Britain, the two best mod players were probably: Ian McLaggan of The Small Faces (listen to some of their instrumentals as well as rock'n'soul tracks like
Song of a Baker and
Afterglow); and of course Steve Winwood - I mean the Spencer Davis Group tracks,
Keep on Running,
Gimme Some Lovin' and
I'm a Man all piss all over anything that The Who have to contribute to the history of the organ.