Adult Master Cash has FHGs for BDSM/Bondage, Blondes, Brunettes, Lingerie/Leather/Latex. Panties, Nylon/Pantyhose, and Pregnant,
Fetish Affiliates has FHGs for Bondage/Femdom/CBT, and Pantyhose/Nylon/Lingerie sites.
Pimp Roll has Glasses, Pregnant, Redheads, Panties, Pornstars, and Nylons. Their DVD download site has FHGs for most of the niches. The AVP section also has some niche FHGs.
NS Cash has galleries for some niches.