Two nested divs vertically filling parent div

[John Hamm]

For this question, please reference:
http://www.hammoco.com/tests/example.gif

Is there a way using CSS to set the height of a DIV to the remainder
of the vertical space in a parent DIV? Similar to "TD WIDTH=*" but
for height? If not, what is the correct way to handle this in CSS?

In the image above, div1 is explicitly set to a height of "50px".
div3 is the parent div, set to a relative height of "100%". div2 is
below div1 (both inside of div3). div2 needs to fill up the rest of
the vertical space.

I'm going to be using this solution for both the screen and printer
medias.