The space elevator
This is a beautiful interactive webpage to illustrate the height/altitude of different things and how a potential future space elevator would relate to them.
If this had been done as a text page or even a page with a few illustrations it would have not have had the same impact. It even has elevator music you can listen to while you ascend the atmosphere.
Get your mouse scroll wheel (or you page up key) ready.
(Also have a look at some of the other pages on the site)