http://gimp-savvy.com/BOOK/ This is an excellently written book by Carey Bunks, and published by New Riders Publishing
www.newriders.com c.2000, which explains all the basics for Gimp.
It was brought to my attention by an associate at MyPCLinuxOS named CtrlAltDel
A "must" addition for any graphic's user's library
There is also a French version online
http://www.linuxgraphic.org/grokking/ as well as the tarball (en-us) download
http://gimp-savvy.com/BOOK/TarDist/Grokking-the-GIMP-v1.0.tar.gz