Proposal: In my opinion there should be a site that also includes BDSM, fetish and related practices. Since the overlap between BDSM and sex generally are pretty big in my experience; including it in Everything You Always Wanted to Know about Sex but were Afraid to Ask only seems logical to avoid separation of the knowledge base. Currently the definition of said site, from here known as EYAWKASBWATA, does not allow for discussions about things that aren't strictly sex which would exclude many practitioners of BDSM and other kinks.
This question predates two renamings of the proposal; BDSM is well-covered under any form of the name. Wikipedia is about as close as you'll probably come to authoritative:
BDSM is an erotic preference and a form of sexual expression involving the consensual use of restraint, intense sensory stimulation, and fantasy power role-play.
There's no need for any extension of the scope of the site: BDSM falls within the scope of sexuality. I'm sure that as always there will be debate on meta about particular questions, but on the whole, it is absolutely on topic.