security resources

hackmes - a series of challenges designed to teach/test web app hacking tesh
hackademic challenges - a downloadable series of vulnerable web app environments intended for teaching secure web programming practices
hacmebank - a vulnerable .net app
metasploitable - a complete exploitable virtual environment for testing various metasploit exploits
redhat 6.2 iso - the most vulnerable operating system in history
modsecurity challenge - a set of vulnerable webapps designed to showcase modsecurity's capabilities
owasp webgoat - a vulnerable .net app

howtos ebooks collection security related videos including defcon/blackhat talks