http://zingchart.com renders in HTML5 Canvas and/or SVG, so it will render on older Androids that don't have SVG support. Also VML for auto fallback to IE6 w/out need for ExCanvas.
transparency: I'm on the team. abegin[at]zingchart.com ^Andrew
i was hacking around under the covers of Mixpanel's 'Platform' a while back and if memory serves, they wrapped highcharts into their api for that product.
I always felt there were lots of gymnastics required to get data into a suitable format for Google charts (filling zeroes in time series, tough to work with multiple series, etc)
