I use OpenOffice Calc, not Excel, but same basic idea. In my case, I use it for a couple of things.<p>1. A file viewer for certain kinds of data (eg, CSV files and the like).<p>2. A quick and dirty way to get simple summary stats from some data. Spreadsheets make it pretty easy to point at some data and get things like the mean, median, mode, std deviation, etc.<p>3. Quick and dirty plotting of small amounts of data. This use isn't as frequent for me, as I tend to use GNUPlot for most of this kind of stuff, but sometimes if you're already in the spreadsheet program poking at some data, you want a chart with a trend-line or something.<p>4. Exploratory models to play with "what if" analysis. Useful for a first pass at coming up with financial projects, evaluating pricing models, etc. The nice thing about a spreadsheet for this is that you write up all the various formulas you care about, and then you can update one cell and quickly see all the updated values. In a sense, spreadsheets are an implementation of a sort of Dataflow programming[1] and this kind of thing can be very handy.<p>It's good for getting answers to questions like "If I want this company to generate $1MM in revenue this year, and we set the price for our product to <i>z</i>, how many customers do we have to sign up?" and others of that nature. Of course there are plenty of other ways to do this kind of analysis, but spreadsheets are pretty convenient here.<p>[1]: <a href="https://en.wikipedia.org/wiki/Dataflow_programming" rel="nofollow">https://en.wikipedia.org/wiki/Dataflow_programming</a>