[cpred]

I've seen most use Excel in finance and office environments. Usually basic stuff like sorting, calculations, and formatting. Cobra has the right idea with some pivot tables for summaries and vlookups for lists and comparisons. My experience has been in programming, most apps that I write, users usually want data export from a database as an Excel file (or .csv). Learning Excel has been helpful to me as well as using libraries like PHPExcel that dynamically creates Excel files from a database via the web.