A plugin to generate bar graphs from an array of numbers, with a simple API and flexible options.
Lictalon recently published their Bar Chart plugin to GitHub. It's a great little plugin that provides for a variety of bar chart formats, allowing you to easily graph value transitions. You can display positive and negative numbers, or both, and spread them over a growing array. Set-up is easy and the API simple to integrate. There's a forum thread to discuss the plugin too.