What a spreadsheet does very well is allow you to quickly run a large set of simulations right next to eachother for comparison. This can be useful in asking questions like, "if we charge $x, and we have $y in fixed expenses, what should our target of support personnel to customers be?"
I usually use spreadsheets only as data entry software and then R does the rest.
You definitely can do it in R, but the formulas are trivial anyway and writing them in code takes as much time as in Excel, can you help me understand what I could gain by using R here?
When I worked in Wall Street level finance, basically none of the analysts bothered to use anything more than cell address, e.g. /[A-Z]\{0,1}[0-9]\{0,3}/. They basically treated naming their variables like most software engineers treat commenting their code. That shit was impossible to follow because.
The individual formulas may be trivial, but when you have a complex model with many pages representing different aspects of the business internally and external macro aspects, it can get messy fast.
This looks promising: http://wiki.openoffice.org/wiki/R_and_Calc