Beryl has a couple of great plugins for organising applications that have a proliferation of little windows like the gimp or kopete, or if you want to group windows associated with a project you are working on.
Normally with these types of applications, you end up "alt+tab"ing all over the show to find the right window. The grouper and scale plugins allow you to organise and find the windows you want fast.
GROUPER PLUGIN AND TABBED WINDOWS
The grouper plugin allows you to join various windows into groups, and perform actions on all the windows as one. For example, if you resize one window in a group, all windows are resized. If you move one window in the group, they all move.