vizkit.js is an opinionated little charting library built on top of the amazing and wonderful d3.js visualization framework. For examples of some of the charts currently available, have a gander at the documentaion.
To hack on an individual chart type, add a new .js file to the src directory (or use an exisiting one), ensure it is included in the src list in the Makefile and then run:
$ make clean
$ make vizkit.js
This will generate a new file with your additions. vizkit.js is still very much a WIP, pull requests are welcome!
( uglifyjs command line tool is needed to minify file, download it through npm )