Yes, I've seen it used as a spreadsheet, to crunch numbers. I've also seen people sit down with a calculator and compute cell values themselves, blissfully unaware that the software could do it for them. Excel is a tool for lining up numbers.
We've all seen Excel CSV files used for reporting and data interchange because they're easy for programmers to generate. I've seen an application's configuration managed by tweaking a CSV file in Excel and uploading it to a server. Excel is a tool for separating labels from values.
I've had screenshots pasted into Excel and attached to an email. Excel is an ubiquitous file format.
I've received an entire application wireframed by the accounting department, with each screen drawn with filled-in ASCII-art columns on its own worksheet and every button hyperlinked to a worksheet showing the next application state.
That really threw me off when I saw it. But when I look back, I realize just how clever it was. Front-end developers are always praising grid-based design, aren't they? That's exactly what what Excel was being used for. Excel is the first layout grid many people encounter."