There is a PEMBLE board here at Ancestry.Com, and anyone doing PIMBLE research should check the messages there as well.
The PIMBLE spelling dates back centuries, but of course, records (both here and in Britain) vary and alternate spellings do occur -- PYMBLE, for example. Pimbell, Pimbel, and Pymbel are just a few more of the variants I've seen.
Since the PIMBLE spelling seems to have regularized -- at least in the U.S.A. -- more than 100 years ago, it seemed worthwhile to ask Ancestry.Com to set up a board specific to that spelling.