GIMP Plugin Registry

Registry FAQs and How-To's

http://registry.gimp.org/node/23868

GIMP Add-ons: Types, Installation, & Management

This covers how to install and manage brushes, patterns, palettes, gradients, scripts, and plug-ins, etc.
http://libregraphicsworld.org/articles.php?article_id=30

How to Install Scripts and Plug-ins for GIMP - Beginners

http://allthingsgimp.blogspot.com/2009/09/gimp-how-to-install-scripts-pl...

GIMP Help & Tutorials:

http://gug.criticalhit.dk/
http://www.gimpchat.com/
http://gimpforums.com/
http://www.gimptalk.com/ - a good site, but usually down
http://www.ghuj.com/
http://www.gimpusers.com/tutorials.php
http://gimpology.com/
http://gimp-tutorials.net/
http://www.pixel2life.com/tutorials/gimp/ http://meetthegimp.org/

How Do I....?

Rotate a brush - http://registry.gimp.org/node/583
Load images on the internet - http://registry.gimp.org/node/25562
Repair old photos - http://registry.gimp.org/node/23760
(More links to come, keep checking back)