I came across this while working with a spreadsheet that was perhaps a little too fancy to come over from Excel to OpenOffice Calc. Let's say you keep a spreadsheet full of various numbers, and they fall into about five or six categories. You have a bunch of things that are categorizable as:
Gnumeric is a spreadsheet application included as a part of the GNOME Office suite. It supports a slew of different formats, including Microsoft Excel, CSV, OpenDocument, and LaTeX, just to name a few. It copies most of the features available in the more ubiquous, proprietary spreadsheet programs, including charts, random number generation, statistical analysis, styling, and batch processing.
Let's say you've got a bunch of data: addresses, or lists of your DVDs, or whatever. It's not world-changing high-transaction information, but you want it in a good storage format. Do you create a spreadsheet and put your info in that, or do you go straight for the higher-end solution and create a Base database?
If you spend all day in spreadsheets, sooner or later you want something to help you spot what's important or different. The motion study expert Frank Gilbreth told factories to paint parts different colors to help factory workers spot the right pieces more quickly; Calc has roughly equivalent features to help point out the different types of data you're working with.