Charts in Rails

We have been working on a project that deals with server data where charts are worth a thousand words. I always get requests for various charts and in the past I’ve used Gruff to produce them. Gruff is a great library and the results look good too! However, recently I’ve have had more demanding requirements to provide more dynamic behaviour on the charts. Users wanted to be able to interact with the charts in various ways and drill down to gather more information.