http://www.oasis-open.org/committees/docbook/DocBook from its creators

http://www.oasis-open.org/docbook/documentation/reference/html/docbook.html The complete DocBook Guide Online

http://sourceforge.net/projects/docbook/ DocBook@SourceForge

http://sourceforge.net/projects/openjade/ Top Open Source XML -> Whatever translator

http://www.tldp.org/LDP/LDP-Author-Guide/ The Linux Documentation Project HowTo (essential explanation on how to make all things up and running)