I came across this video recently from Seattlefoodgeekcom. He uses stainless steel instead of ceramic for a pizza stone to cook pizza on the grill.
Check out this video on YouTube:
[ame="http://www.youtube.com/watch?v=YyVz84m2KLM&feature=youtube_gdata_player"]Tested: Cooking the Perfect Pizza at Home - YouTube[/ame]
It was very interesting.