Wallpapers and Walling

I've recently started to create walls again, since exams are almost over and I have the whole summer to myself (with new dual monitor setup ^_^). I used to be an AMV creator, but I've given up, because it's just too time consuming, and a pain in the rear with all the copyright issues for songs on Youtube :(

My first wall was sent to session zero (I'll be making it go through a complete overhaul soon), and my second one was accepted. I'm thinking about trying something new for my third wall, something that involves water, and overall a much darker, more spiritual wall. I've come up with the idea of having rippling water as the background, and rain falling from the sky, with a bird's eye view. I've done quite a bit of hunting around, and I couldn't find any tutorials on it, I guess I'll have to figure out a way to draw the rain out, create some type of depth of field.

I use GIMP, but I'm willing to hear any kind of tutorial on how to make falling rain from a top view (if there are brushes, that'd be great too).

Arigatou Gozaimasu~!