Useful websites/organizations are:

Recover Your Life (support and an on-line community)
Secret Shame (offering information and support)
LifeSigns (a support network with fact sheets)
Psyke.org (including lots of references and personal stories)
Bodies Under Siege (support forum)
Blood Red (community support)
Lysamena Project (advice for friends and family)
Mind (mental health support)
WebMD (information reviewed by doctors at Cleveland Clinic Department of Psychiatry & Psychology)
Wikipedia (information submitted by anybody)
Selfinjury.org (helping yourself)
S.A.F.E Alternatives® (including helpline)
Selfinjury.net (including message board)
HealthyPlace: Self-Injury Community
Eqi.org (looking at invalidation as a cause)
About.com:
     information and help
     for parents of teenagers
PAIN (information)
HelpGuide.org (information)
THE SECRET CUT: Understanding Self-Injury (Warning: contains rather explicit photos!)
Self-Injury: A Struggle (with information, FAQ, forum, resources, quotes from self-injurers)
Equilibrium (user-led self injury awareness organization, UK)
Focus Adolescent Services (includes also book recommendations)
The National Self Harm Network (a support site for self-injurers)
To Write Love On Her Arms (including a story about a self-injurer by Jamie Tworkowski)
Cornell Research Program on Self-Injurious Behavior in Adolescents and Young Adults (including a publications list)
National Center of Trauma-Informed Care: "Living With and Healing From Self-Injury" (PDF)
"Self-Injury in Children" by Leah Davies, M.Ed.
Camelot Foundation / The Mental Health Foundation
     "The Truth About Self Harm" - Young People's Report (PDF)
     "Truth Hurts" - Report of the National Inquiry into Self-harm among young People (PDF)
Young People and Self-harm (UK information resource for young people who self-harm, their friends and families, and
      professionals working with them)
The Self Injury Anthology Project (music, literature, movies, TV dealing with the subject matter)
bipolarworld.net (including forum, chat room and a few personal stories, centering on bipolar disorder)
Borderline Personality Disorder (general information, personal accounts and poetry)
Casa Palmera - informative articles:
     Self-Injury Among Those With Eating Disorders & Addiction
     Self-Injury: Steps Toward Recovery
facetheissue.com (dealing with self-injury, anorexia and bulimia, alcoholism, abuse, drugs, etc.; includes forums and blogs)
Cleveland Clinic Center for Consumer Health Information
SI - The Emergency Room
Helen's World of BPD Resources:
     List of SI resources
     Support boards and chat rooms
Online Dictionary of Mental Health (listing of SI resources, incl. chats, forums and personal pages)
Mental Health America: Factsheet on SI warning signs (with help links)
CoolNurse.com: "I Keep Cutting Myself and I Can't Stop!"
TheHelpline.net: "Self-Injury: A Search For Understanding"
SelfhelpMagazine: "SELF-INFLICTED VIOLENCE: HELPING THOSE WHO HURT THEMSELVES" by Tracy Alderman, Ph.D.
Hurting Within (general information and personal accounts)
The Royal College of Psychiatrists, UK (general information)
Crescentlife.com (general SI information)
UPMC
AAPEL (article on connection between borderline and self-injury)

News items on self-injury include: