Highcharts, Google Chart, groupdate, jQuery (for AJAX), and iso8601.js (date parsing) definitely do the heavy lifting. My favorite part about the library is yo

Highcharts, Google Chart, groupdate, jQuery (for AJAX), and iso8601.js (date parsing) definitely do the heavy lifting. My favorite part about the library is you don't need to worry about getting the data in correct format. It just works with existing Rails methods, like ActiveRecord's count. Also, Google Charts look a lot better with a little bit of custom styling.