The Creative Commons Music Sharing license marks work as legal, promotes it through Common Content and makes it searchable with the Creative Commons audio search engine. It lets users know that you own your music, but allows them to download, share and copy it.
Common Content is a collection of Creative Commons licensed materials. The Creative Commons search engine helps users search for material that is under a Creative Commons license, with options for commercial purposes and derivitives.
The Creative Commons licenses for software adds to the Free Software Foundation's GNU License by including an easy to read version of the license and a meta-license that can be read by search engines so people can find your programs. Go to CC-GPL or CC-LGPL for more information.
If you want to hold onto your rights for less time than a full copyright provides, a Founders Copyright could be for you.
The contributor enters into a contract with Creative Commons in order to guarantee the release of the work into the public domain after 14 or 28 years.
The Developing Nations license addresses the lack of access in developing nations to new work by allowing uses of work in developing nations while maintaining full copyright in developed countries.
There are three Sampling Licenses available:
The Sampling license allows users to manipulate pieces of a work for any use except advertising. It prevents distribution or copying of the entire work.
Sampling Plus allows manipulation of pieces of work, as well as noncommercial copying and distribution of the entire work. Again, use for advertisement is not allowed.
Noncommercial Sampling Plus restricts derivatives to noncommercial uses only.