Freedb
FreeDB is a database of compact disc track listings where all the content is under the GNU General Public License. It was originally based on the, now commercial, CDDB (compact disc database). As of May 2003 the database holds over 978,000 CDs.
Motivation
With the new terms of licence for accessing CDDB, some programmers complained that the new licence includes certain terms that threatens them in a way they cannot accept: If you want to access CDDB, you are not allowed to access any other CDDB-like database (such as FreeDB, for example) and - while accessing the database - the programmer has to ensure, that a CDDB-logo is displayed (Funny sidenote: One programmer told me, that his cd-player will be banned if he is refusing to display the CDDB-logo. His software is a console-based program - it does not produce any graphical output - for blind people...).
In March 2001, CDDB (whose name had changed to Gracenote) banned all unlicensed applications from accessing their database. New licenses for CDDB1 (the original version of CDDB) were not available anymore, as they wanted to force programmers to switch to CDDB2 (a new version incompatible with CDDB1 and hence with FreeDB).
The initial CDDB license was GPL, and many people who submitted CD information without charging anybody and thinking their help would remain free.
FreeDB is used primarily by media player and CD ripper software.