This is pretty cool, check this out:
http://www.primaxstudio.com/stuff/scale_of_universe/
It's an animation where they take the sizes of various things, from the smallest things in existence to the largest and they put it on a slider scale so you can slide from smallest to largest. Along the way they include interesting facts and figures. It's set to go from "human size" (1.7 meters) initially, but you can go all the way down to the smallest thing that humans know about, then move the slider up through atoms, pit on a CD, bacteria, microprocessors, smaller organisms like ants and worms, then up to human-sized and further into the size of mountains, the earth, distance between earth and the moon, allllll the way up to the full length and breadth of the area that humans can see in our telescopes and finally to the size of the entire universe.
Enjoy!