Supposed to be to teach kids but I love it.
http://www.documaga.com/wp-content/uploads/2010/02/scaleofuniverse.swf
Click play and scroll the bar to the left to downsize, then to the right to get bigger.
http://www.documaga.com/wp-content/uploads/2010/02/scaleofuniverse.swf
Click play and scroll the bar to the left to downsize, then to the right to get bigger.