Turfgrass Water Conservation Alliance (TWCA) created the Irrigation Calculator (based on this calculator from Pennington) to help end-users predict the runtimes of their irrigation systems.  Simple. 
TWCA collaborated with a network of public and private researchers including Oregon State University, University of Washington, University of Arkansas, and NexGen Plant Science Center, on a series of multi-year inquiries to answer some basic questions about site specific conditions.
The Irrigation Calculator is simple. Click the greenness of your grass (fun fact: during development we called this the "lush level").  Know the irrigation rate and weekly frequency. Remember where you live.  It's true, there are some curveballs in there; not everyone knows if they have TWCA Qualified turfgrasses, but generally, pretty spoon and June.

The calculator itself is an example of interdisciplinary cooperation on a public/private partnership resulting in an immediately useful tool.