Source (link to git-repo or to original if based on someone elses unmodified work): https://github.com/Chumpen/Splash-Screen-ART-for-GIMP-SET2
Make with GIMP 2.8 and Blender
By Chumpen Suksapar
Create a splashes directory in your in your personal GIMP folder (/home/user_name/.gimp-2.8 on Linux, C:\Documents and Settings\user_name\.gimp-2.8\ on Windows).
Copy your image(s) into this splashes directory. On start, GIMP will read this directory and choose one of the images at random.