The answer that came back from the echo chamber was "in your oven". But when you store these things in your oven you loose an oven rack. Or you have to heft this heavy thing in and out when you need the rack it sits on.
Finally, I've solved this problem. Actually I've been doing this for years, but have just now gotten around to writing it up for Instructables. I'll explain how to easily regain your oven rack . . . and why pizza stones suck.
* I feel the need to qualify the suck comment. Obviously from the picture my pizza stone is old and well used. Stones are much better than baking sheets . . . by miles. If your choice is to cook a pizza on a thin baking sheet or a thicker baking stone, then you'll be much happier with the stone.
Step 1: Needed Things
---Fire bricks (sometimes sold individually at home improvement stores)
---A heavy hammer
---A brick chisel (a tile/brick saw would also work well if you happen to have access to one)