Here's my first example map I made when I was bored! Self-explanatory: It's a map with thunder (or was it lightning?) and rain, using a different approach instead of the one in the rain tutorial. Other stuff is in the readme, including other features in the map and installation.
QUICK EDIT!: Fixed some face splitting on the street lamps and added clip brushes around the tree to simplify clipnodes (I think they were called clipnodes?).
Cool Idea!