Three tours starting at one meter in size zooming down to 1 femtometer (10^-15, the size of quarks). Each view is one-tenth the size of the previous. One tour goes into the human body, starting at a full-sized human, zooming in on a mosquito, zooming in on human cells, zooming down into DNA, into molecues and into their components. Another tour goes into a laptop computer, and a third goes into an LED light.

Fascinating and very well put together. Link from madscientistgirl, who also went to the effort of capturing this cool screenshot from the site.

Link