BDSM and Kink

run by Terrence Higgins Trust aimed at gay men interested in rough sex, S&M and other other hard core sexual practices. The site combines facts about sexual health and recreational drug use with information about sex acts and rough sex. Useful info for people interested in BDSM as well as recreational drug use in sex .

Website promoting the concept of "BDSM Rights": the belief that people who's sexuality or relationship preferences include Bondage and Discipline, Dominance and Submission, or Sadism and Masochism ("BDSM") deserve the same human rights as everyone else, and should not be discriminated against for pursuing BDSM with consenting adults.
www.bdsmrights.com

A United Kingdom campaigning organisation for informed and consenting adult sadomasochists. It exists to represent the UK SM scene and to campaign on its behalf.
www.uksmpride.org

National coalition for sexual freedom incorporating Kink aware professionsals. The resource for people who are seeking psychotherapeutic, medical, and legal professionals who are informed about the diversity of consensual, adult sexuality.
www.ncsfreedom.org/kap

John Pendal is a former International Mr Leather who has been an ardent campaigner for SM rights with the Spanner Trust and is involved in a educating people about BDSM.  He's recently started publishing an online column: 
http://www.pawscave.dircon.co.uk/IML/being57.htm