I was using ObjectDock, but then someone on Flickr uploaded their image with this dock by RocketDock and I immediately started using it. (Both dock sources have their advantages. I greatly enjoyed ObjectDock and it has its advantages over RocketDock, but this is simply cooler.)

(Left to right: My Computer, my personal folder, My Music, my external HD, separator, Firefox, Songbird, MS Paint, and Word Perfect)

-CF