I've put up video clips of wingsuits before, but this one caps them all, I think. It's highlights of the jumps made by Phoenix-Fly during 2009.
Amazing stuff! I'm particularly intrigued by their low passes over rocky outcrops and hills. They must be able to judge their 'sink rate' to a nicety in order to be sure they'll have enough altitude to make it. One misjudgment, and they'll never make another!
I recommend watching the video clip in full-screen mode, if your monitor is sharp enough. It's pretty spectacular.