The Scale of the Universe

The Scale of the Universe is a small interactive flash site that lets users see the relative scale of objects in the universe. It begins at the size of a human, but quickly zooms in to the relative size of an atom, or zooms out to encompass the size of the observable universe.

Unfortunately, if you are viewing on a device that doesn't support flash, such as an iPad, the site cannot be used interactively. However there is a Youtube version that shows the scale zooming in and out at a fixed rate.