Photrio Forums – Formerly APUG.org, this forum is bursting with knowledgeable darkroom folk:
https://www.photrio.com/forum/home
Unblinking Eye – This extremely helpful and informative site has been around forever:
Pakon.au Forums – this brand new forum will hopefully gain a bit of traction and get Pakon scanner information into a searchable place:
Pacific Rim Camera Reference Library – a fantastic collection of historical photography sales and instructional literature.