Internet Mental Health An excellent mental health resource. Information on disorders, medications,

Mental Health Net An informative site. Their web community contains a variety of forums and chat rooms. One of the best, definitely 

Depression Alliance

@ease -  A mental health site for young people

Healthyplace.com - a good site for support, lots of chat rooms and message boards.

Depression Screening Test

Something Fishy - A wonderful site on eating disorders, information and resources, and online support.

The Mental Health Foundation. This is a British site, contains some useful info

Bipolar Disorder Sanctuary - Offers brilliant information and support to sufferers and their friends and families

Borderline Personality Disorder Sanctuary - Again, like the bipolar Sanctuary site, the borderline site offers a huge amount of information and support.

SIARI - Free information about self-injury & related issues (dissociation, eating disorders, childhood trauma, abuse, etc). Research based, with extensive input from self-injurers. A valuable online resource for self-injurers, their loved ones, friends and supporters.