would you be interested in adding "conversion efficiency" (http://braukaiser.com/wiki/index.php?title=Understanding_Efficiency#Conversion_efficiency
I have been pushing this idea of efficiency, which reflects the amount of starch converted in the mash, for a few years now.
The inputs for the calculation would be:
amount of water in the mash
average extract potential of grain (should default to 82%)
grain moisture content (should default to 4%)
mash gravity reading (Plato, sg or Brix. The latter should do an automatic refractometer conversion and would be the most practical one)
the result would be
conversion efficiency (percentage of starch converted in the mash).
This is one of the calculations that I do most often when I brew since I'm interested in getting to 100%.