I'm a techno-newbee, but I set up a blog with a time-lapse batch of photos at blogger.com I called it "pond & waterfall." I couldn't figure out how to link anyone who's interested from here to blogger.com
As far as bridge sizes go--I was suprised how long my span needed to be to work right. That log above is 19' 6". I knew I wasn't going to be able to buy something off the shelf.