Licenses

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/

Free Art License
Copyleft license applied to artistic content and projects.
http://artlibre.org/licence/lal/en/

GNU Free Documentation License
A version of the GPL for reference material.
http://www.gnu.org/copyleft/fdl.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, either commercially or noncommercially.
http://www.rpglibrary.org/oogl/

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://www.dmoz.org/license.html

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

Kuro5hin.org: Creative Commons - NC Licenses Considered Harmful
"One particular licensing option...is a growing problem for the free content community. It is the allow non-commercial use only (-NC) option. The 'non-commercial use only' variants of the Creative Commons licenses are non-free, and in some ways worse than traditional copyright law -- because it can be harder to move away from them once people have made the choice." <small>(September 11, 2005)</small>
http://www.kuro5hin.org/story/2005/9/11/16331/0655