The GNU project : http://www.gnu.org/
The OpenSource Initiative : http://www.opensource.org/
FSF Europe : http://www.fsfeurope.org/
Bibliography :
David A. Wheeler's "Why Open Source Software / Free Software (OSS/FS)? Look at the Numbers!" : http://www.dwheeler.com/oss_fs_why.html
Eric Raymond's "The Cathedral and the Bazaar" : http://catb.org/~esr/writings/cathedral-bazaar/