Tony Gemignani's Respect the Craft Baking Steels. That's right, 2 Steels are better than 1.
Here is the basic concept from Tony's book, The Pizza Bible. You preheat the oven for an hour with two Baking Steels to get them up to temperature, then you switch the oven to the broiler setting for a few minutes while you get the pizza ready for baking. The pizza cooks on the upper Baking Steel with the heat of the Baking Steel below it and the charring heat of the broiler above it - just as it would cook both from above and below in a wood fired oven-and then gets a final toasting on the lower Baking Steel to crisp the bottom.