I am starting to arrange the Brandenburg Concerto No 3 by Bach for organ, has I dont think it or any of the Brandenburg Concerto's have been arranged for organ.
Im not finding it that difficult to arrange (as I have sibelius music software), but i havent tried to play on my organ yet - Ive got to play the double bass and cello parts with my feet!
I decided to arrange it after listening to it played with a baroque orchestra thinking ''I can imagine this on the organ''

Any one else into arranging things for organ or do you all cringe at the mere thought of organ arrangements?

I think the reason these might have not been done is that being one of the finest pieces ever written, even removing one part from these pieces seems to somehow diminish them. Good luck though, and i look forward to seeing your results.