If you are looking for a simple, but highly effective three-step passing package take at look at the Shallow Cross Passing System.
In the video below Mark Richt, Head Coach at the University of Miami, explains the shallow, choice, and flat combination routes that are a part of his Shallow Cross Passing System. Coach Richt explains the quarterbacks reading progression. He also covers the adjustments to various blitz. These interchangeable combination routes can be easily run from a variety of formations creating problems for the defense.
For more information about the DVD that this clip came from click the link Mark Richt: The Shallow Cross Passing System
The YouTube video has sound, so please make sure that the sound is turned on and that you have access to the site (some schools block access to YouTube)