There were a few which worked on browser window resizing, not mouseover. I think the first one brought to my attention was http://therissingtonpodcast.co.uk/ ht

There were a few which worked on browser window resizing, not mouseover. I think the first one brought to my attention was http://therissingtonpodcast.co.uk/ http://therissingtonpodcast.co.uk/ (footer), then http://www.silverbackapp.com/ http://www.silverbackapp.com/ and http://dromaeo.com/ http://dromaeo.com/