I recently found some neat products at "The Tile Shop", a chain here on the Eastern side of the country. Essentially, it makes building a shower tile floor pretty fool proof- from the waterproof membrane to a plastic thing that connects to the drain that provides the right pitch in the floor.
The Tile Shop | Product Detail
Gives you the ability to make a custom shower floor for relatively small $. I haven't used it yet, but will when I do our shower this Summer.