What can't you do in Excel?
chris_l: For conventional programming I've been working on laying the logic out as a graph automatically. Instead of cryptic formulas in the cells, you would have an easy to understand graph that shows how information is related and computed. In addition the intermediate results for selected input values could be shown next to the nodes and links, to allow inspection of the computation.This could be adapted for the spreadsheet concept. Actually, it might be more appropriate there.