I've made some further additions to the BrewCalc spreasheet.
It now has a total of five worksheets. The newest worksheet calculates a pitching rate based on George Fix's pitching rate numbers from An Analysis of Brewing Techniques. It provides pitching rates for both ales and lagers. If you want to see the math at work here, check out Jamil's page on Proper Yeast Pitching Rates. It's quite straightforward.
Additionally, there are now a few cells that are automatically populated by figures determined on the first sheet "OG, IBUs, ABV%, etc." This way you don't have to enter certain figures redundantly. Since batch size is a variable that is used in many of the calculations, BrewCalc will now use the figure provided on the first worksheet to determine a host of other numbers. You won't need to go back and forth to change this yourself. This should make it a bit easier to work with.