Pivot tables are in contrast to popular belief not just an Excel feature but present in a lot of applications dealing with tabularly structured numerical data – pivot tables are the visual and interactive result of a general concept of data aggregation depending on categories. LibreOffice (check out the article on it), OpenOffice and R by libraries like reshape offer this technology targeting at a different audience. If you understand pivoting in one of these tools, you pretty much got it for all of them.
At my work I am offering a workshop on pivoting with Excel 2010 and so I came up with a chart boiling down the concept of using pivot tables so it fits on a sheet of PDF.