Current estimates==                                                                                                                   There are some  400 billion stars in the milky way and some  50 billion planets...

I just came across this little gem.  Someone has created an interactive flash where you can slide between size scales, all the way from the very smallest (Planck Length) all the way to the very largest (size of universe).

And it has wonderful music to boot!  So put on your headphones and

mainline the wonder:  http://www.newgrounds.com/portal/view/525347