Psychology Classroom at AllPsych Online
Has a lengthy section on Psychiatric disorders and includes an Index matching the disorder to its category and code in the DSM-IV. See the 'Reference' section for a Psychology timeline and dictionary as well as biographies and Medication guide.
From CHOICE Reviews: AllPsych Online is "series of free general psychology e-books written by Christopher Heffner, a licensed Florida psychologist, and the Heffner Media Group. They include Psychology 101, Statistics Primer, Personality Synopsis, and Research Methods."