PimpRoll has Real Big Nudes. Their DownloadPass site has a FAT category, as well as a BIZZARE category. Their AVP section has Big & Beautiful Whores, Big is Beautiful, Fat Girls XXX.
SunnyDollars has Bondage Ladies and BBW Orgies. They also have quite a few other interesting sites, plus, most mainstream niches.
TopBucks has Fetish Hell and LArge Girls XXX.