The Scale of the Universe
IBM created a video entitled "The Powers of Ten" back in the late 1970s that demonstrated the scale of things in the universe by zooming out a distance equal to adding another zero to the starting scale and then zoomed in by removing zeroes from the number down to the smallest distance known.
The video is a great demonstration of the vast scale difference of the universe, but since it is a video, you can only just play it. Recently I came across another demonstration of the powers of ten that can be opened in a web browser and, using the scroll wheel on the mouse, can be zoomed in and out under the users control.
The file can be saved to the local system and opened up from there, so an Internet connection isn't needed.