UPDATE 10.02.2018: A new version of the plugin has been released, see this blog post.
An interactive Pivot Table lets the user analyze a data set by selecting which fields to use as rows and columns in a grid. You've probably seen this in Excel, something like this:
I've created a region plugin for Apex which turns any SQL query into an interactive pivot table. The plugin is a simple wrapper for a pivot table written in Javascript by Nicolas Kruchten. There's also a nice tutorial page that explains the user interface.
This animated screenshot shows how the plugin is set up and used in Apex:
Note that you can have multiple Pivot tables on the same page if you want. You can also turn off the interactive features if you just want to display a preset summary.
You can download the plugin here. Enjoy!