APA's Help Center The American Psychological Association website offers educational information about topics including anxiety, depression, ADHD, and other mental health issues.
Acceptance and Commitment Therapy (ACT) The Association for Contextual Behavioral Science website contains useful info about ACT and the theory on which it is based - Relational Frame Theory.
Beck Institute Youtube channel Videos from the Beck Institute, founded by cognitive therapy pioneer Dr. Aaron Beck and carried onward by his daughter, Dr. Judith Beck.
ABCT Fact Sheets on mental health topics from ADHD to Worry Useful information about the psychological aspects of a variety of conditions, including domestic violence, cancer, combat-related stress, marital stress, etc.
What to expect from cognitive-behavioral therapy (CBT) A nice overview of the rationale for CBT and what to expect from psychotherapy.
Exposure Therapy for PTSD A good summary of exposure-based therapy for treating Post-traumatic Stress Disorder (PTSD).