Excel is a pretty amazing piece of software. Previous place i worked at -- a medium-size insurance company -- did all of their monthly expense calculations in u

Excel is a pretty amazing piece of software. Previous place i worked at -- a medium-size insurance company -- did all of their monthly expense calculations in uber-complicated spreadsheets and then exported the results to AS/400. Part of their issue was that training staff became an increasingly complex task because of the structure of the data in the sheets some of which had to be imported from a 3rd party source. I have never seen Excel used to this extent until i was brought in to convert these sheets to a web app. We ended up building a custom DSL based on mathematical expressions, an in-browser IDE for accountants to configure formulas in the system and a full-blown custom report builder. It was by far the most complex project I've ever designed and it had an immense impact on how i look at advanced Excel users today.