Since I did start this thread, thought I'd repost this just to keep it fresh:

Okay, we did the Free Brushes for GIMP, now we do the free Plug-ins. What exactly are Plug-ins? Well, plugins are add-on programs aimed at providing additional image effects or performing tasks that are impossible or hard to fulfill using one program alone.

To that end, here is a link to 20 of The Best Free GIMP Plugins