In the databases mentioned below, you will be able to locate reviews of assessment instruments or tests. In addition, searching the "Tests and Measurements, TM" field with the name of a test in the PsycINFO database and then scrolling down in the article to the "TM" field to show which test is mentioned in the article, will also yield information about particular tests.
ProQuest Dissertations and Theses will have several tests and measures available. As most test copies will be located in the appendix part of the dissertation, search by keyword or phrase and browse to the appendix section to locate the tests.
The National Center for Posttraumatic Stress Disorder has information on measures freely available. However, the assessment tools themselves are available only to qualified mental health professionals and researchers.
The Department of Psychology at the University of Miami has a group of scales available for free if used for research or teaching applications. No permission is necessary.
The Alcohol and Drug Abuse Institute of the University of Washington has developed the Substance Use Screening & Assessments Instruments Database which makes available some instruments used for screening and assessment of substance use and substance use disorders.