I use the charts quite a lot and think they are really nice - a feature I would like to see is the ability to enable item highlighting - for example on a pie chart if the user moves over the different segments they could highlight - we allow our users to double click on a chart item and go a new specific view - however its not obvious to them at the moment due to the lack of visual feedback.
I would also like to see a gauge widget as we are currently having to use gauge.js to fill this gap - other types of dynamic widget such as this would be great.