IT Staff Calculator

In our latest Cookbook, we featured a lot of content about technology planning, technology budgets and IT hiring, and I kept searching for decent formulas, guidelines and calculators to help libriarans make IT decisions.  I didn't find as many as I'd hoped.  So I was glad when Sarah forwarded me a link this week to Lori Bowen Ayres' IT Staff Calculator.  It answers the question, "Given the number of patrons, branches, computers and networks that you have, how many IT staff should you hire?"  If you disagree with the weight she assigns to each factor, you can change the formula to reflect your own perspective.  Does anyone else have tools, templates, calculators and formulas that they use when making budget and staff decisions?