I did that the other night to relax. I'm pretty busy right now at work and don't have much time to do personal illustrations (or anything else really). Plus I lost all the data on my external drive (yes, my back up drive...), which is pretty sad, I have to say, but I'm trying not to think of all I lost.
I don't know about the colors in this one, since it seems to be extremely different from one computer to another (I will have to check I didn't mess with the settings on mine), but I hope it will come up right on your screens.
I just wanted to play with a brush in photoshop and wanted to keep it simple.