Guild Organizer is a mod written originally by Sardonic to help keep track of which alts belong to which characters.
It allows you to:
-Combine characters into an expandable list
-Increases the viewable size of the public and officer note fields
-Allows you to add your own private notes
-Allows a Guild Leader to edit ranks and switch them around in a more friendly environment
-All data is saved locally and it does not communicate with other players
Just as a note, the Guild Control panel is a new feature that hopefully has no bugs, but I have had little ability to test it. It appears to work correctly tho.
Main site that has been getting updated the most is http://wowui.incgamers.com/ui.php?id=23.