Plugins are one of the reasons I really digg Rails. Essentially plugins let me do stuff without re-inventing the wheel. The fewer lines of code I write, the happier I am. I’ve always had a fascination with TreeMaps and could see the idea being useful in a few projects. With the acts_as_treemap plugin I can now immediately implement a TreeMap. Rob Orsini has posted a tutorial on getting up and running.
If you happen to be wondering what a TreeMap is and how it could possibly be useful as an information visualization tool: A picture is worth a thousand words.