This is my new wallpaper (looks great on lightdm) :
I ended with it after following this great tutorial by Blender Cookie.
The shape is generated from a track by Mogwai (friend of the night) and the glowing rainbow colors are at the opposite of the mood of the music video.
The process is quite interesting, and it makes me working in python, so I will do some similar pictures in near future, trying to catch the spirit of the song with the shapes and the colors.
Here you can get the WQHD picture if you want.
This post is also available in french.