Excel is actually a pretty sophisticated tool for end-users. It has a scripting language (VBA), it can pull data straight out of databases via ODBC and it can do sophisticated data visualizations (pivot tables and pivot charts). Its weakest point seems to be the inability to trace and document the complex web of formulas in a spreadsheet - you can't diff the old version of a spreadsheet against a new one and see what changes you made in the formulas. If someone could build a tool that could do that, it might make spreadsheets less opaque and more reliable.