This script generates a poster like the famous Obama "HOPE" one from Shepard Fairey.
Copy it into the scripts folder from GIMP, you will find it then under Filters -> Artistic -> Obama Hope.
If you like it, hug someone.
See also the Che Guevara Script.
An example can be found here:
Update 1: Seperated smoothness option to corn and smoothness with better defaults.
Update 2: Typo threshhold -> threshold.
For all scripts together, go here.