Open Web Application Security Project (OWASP)
http://www.owasp.org/index.php/Main_Page

The Open Web Application Security Project (OWASP) is an open community dedicated to enabling organizations to develop, purchase, and maintain applications that can be trusted. All of the OWASP tools, documents, forums, and chapters are free and open to anyone interested in improving application security. They advocate approaching application security as a people, process, and technology problem because the most effective approaches to application security include improvements in all of these areas. OWASP is a new kind of organization. Their freedom from commercial pressures allows them to provide unbiased, practical, cost-effective information about application security. OWASP is not affiliated with any technology company, although they support the informed use of commercial security technology. Similar to many open-source software projects, OWASP produces many types of materials in a collaborative, open way. The OWASP Foundation is a not-for-profit entity that ensures the project’s long-term success. This has been added to World Wide Web Reference Subject Tracer™ Information Blog.