Many of the features you've requested via Google Chart API forum are now live in the Google Chart API:
- Easily create Sparklines (&cht=ls) without having to manipulate other kinds of graphs.
- Support for Radar charts (&cht=r or &cht=rs) to display data in a polar coordinate system.
- A new Map chart type (&cht=t) which makes it easy to colour countries and regions according to your data.
Some other changes we've made:
- Added scaling for text encoded data
- Added support for negative numbers on bar charts
- Added ability to draw data lines on bar charts
You can read more about all of this -- plus the fact that we've lifted the 50,000 queries per day limit -- on the Chart API site. And special thanks to our Technical Writer Lesley Burr, who put together this documentation in her 20% time.