Graphic Slicing with The Gimp?

Ivo asks: "I'm a webdeveloper working almost exclusively in Linux. But I currently still use Windows to use Adobe's ImageReady, to splice up the designs that we get from our webdesign partners. Usually, if someone asks 'can I do Adobe Photoshop stuff on Linux', the answer is of course, Gimp. Gimp rules. No doubt about that, and I use it all the time. But I miss the features that ImageReady has, like automatic generation of a lot of small images and buttons for a website, including mouseover and mouseoff variants. Doing that manually in Gimp or Photoshop takes hours. Is there a program for Linux, or even better a plugin for Gimp, that does what ImageReady does?" How difficult would something like this be to do using Script-Fu?