GNU Free Documentation License  
   A version of the GPL for reference material.
   http://www.gnu.org/copyleft/fdl.html

Open Content License  
   License for the Open Content Project
   http://www.opencontent.org/opl.shtml

Open Directory Project License  
   The license agreement for replicating ODP data.
   http://dmoz.org/license.html

The Open Book Project  
   Open Content Licence for IDG's Open Book Project.
   http://www.linuxworld.com/linuxworld/idgbooks-openbook/lw-oclicense.html

Open Game License  
   License of the Open Gaming Foundation, as drafted by Wizards of the Coast.
   http://www.opengamingfoundation.org/ogl.html

Free Art License  
   Copyleft license applied to artistic content and projects.
   http://artlibre.org/licence.php/lalgb.html

October Open Game License  
   OOGL. The purpose of this License is to make a rulebook, game manual, sourcebook, supplement, or other written role-playing game document "free" in the sense that everyone is permitted to copy and redistribute it, with or without modifying it, e
   http://www.rpglibrary.org/oogl/

Creative Commons License Generator  
   Service allowing quick and easy selection of one of a range of Open Content licenses to meet a content creators' requirements (concerning attribution, whether commercial use is allowed, and whether modification is allowed).
   http://creativecommons.org/license/