CTF

Live

 * Hack.lu
 * Hack.lu CTF 2010
 * Hack.lu CTF 2011
 * rwthCTF 2011
 * https://wiki.mozilla.org/Security/Events/CTF

Permanent

 * http://www.newbiecontest.org
 * http://www.hackthissite.com
 * http://hackbbs.org
 * http://www.try2hack.nl
 * http://overthewire.org

IRL challenges

 * Insomni'Hack
 * Jurackerfest

Solutions

 * GhostInTheShellcode 2012