GIMP Plugin Registry

It sounds like a conspiracy theory, but it isn't. The pages coming out of your color printer may contain hidden information that could be used to track you down.
See http://www.eff.org/issues/printers and http://seeingyellow.com/

This script helps to detect such tracking color dots in the output of your color laser printer.

All you have to do is:

1. Create a text document with just a few words, some of them colored
2. print it on the suspected laser color printer
3. scan an empty area (e.g. postcard size) of the printed page (600dpi or 1200 dpi)
4. run this script on the scanned image
5. zoom to 100% on the result

After installation you'll find this script in the image context menu (right-click) under: Filters -> Politics.