I've been thinking about my last post, and it occurred to me that some users probably think a database is nothing more than a big, interactive spreadsheet. Result sets are returned as rows and columns, and maybe their reports have graphs, just like in Excel. Heck, maybe they're actually using Excel as a front-end, so of course the database looks like a spreadsheet.
I know when I'm asked, "So what is a database, anyway?" I use a spreadsheet to explain it.
Maybe I have to come up with a better metaphor.