ACT Safer SM Seminars
http://www.safersm.org/
A series of seminars in Toronto on SM technique and safety issues. Presented by the AIDS Committee of Toronto, but the range of information provided goes far beyond AIDS education, dealing with all aspects of BDSM safety, physical and mental/emotional.
Cuir Underground
http://www.black-rose.com/cuiru.html
A San Francisco-based magazine for "the pansexual kink communities", formerly based on a hardcopy magazine, but now completely online. Features book, film and music reviews; weekly BDSM and censorship news; a calendar of events; and articles on everything from stripper burnout to non-monogamy to SM sex magic in Satanism.
Deviant's Dictionary
http://public.diversity.org.uk/deviant/
A dictionary of fetish- and BDSM-related terms. Awkward and unappealling design, but a useful information resource.
Gloria Brame.com
http://www.gloria-brame.com/
Official web site of Dr. Gloria Brame, who Annie Sprinkle once called "the Albert Einstein of kinky sex". Contains tons of essays and articles by Dr. Brame on BDSM and other aspects of sexuality, plus information on her books and therapy services. Highly recommended.
The Frugal Domme
http://www.frugaldomme.com/
A highly useful and entertaining site devoted to practicing BDSM on a budget. They sell inexpensive toys, and also offer a wealth of information on making your own, plus a great deal of general BDSM information, FAQs, humour, a directory of local groups, a message board, etc. A female-dominant perspective, but a lot of the information is useful to anyone regardless of gender or orientation. The site design is overly busy and thus a bit confusing, but otherwise it's an excellent site.