Posted: Aug 16, 2011 10:01 am
I've been doing this for quite a while now.
If you have a big enough grill, you don't even need a stone, you can just get it real hot and then throw the pizza on (you need a pizza screen or pan with holes in it). the burners underneath the pizza need to be on low or turned off, otherwise it will burn.
Stone works better though. Pointer: don't go out and buy a $40 pizza stone. Go to Home Depot's lawn & garden section and purchase one or more sandstone patio pavers. Thicker, more durable, and hold more heat than some crappy bed bath & beyond bullshit, and about 1/10th the price.
I have also seared some steak on that stone with great results.