An extension to The GIMP which allows it to be automated by the use of scripts. Basically, anything that a user could do through the user interface, can be duplicated by means of a script.

This allows images to be created on the fly, and if Nate could ge it to work, would make Everything cooler. For an example of Script-Fu done right, check out http://cooltext.com

see: GIMP, perl-fu.