First, thing I made in GIMP and this was my second attempt.
(I never used gimp before.)
When I did Mx250z's Tut I got his:
http://i50.tinypic.com/abkn6u.png
When I followed JxTutorials I got whats in my sig.
Video Link:
YouTube - How to make a splatter graffiti effect in GIMP (HD)