Bubble charts encode data in the area of circles. Although less perceptually-accurate than bar charts, they can pack hundreds of values into a small space. Implementation based on work by Jeff Heer. Data shows the Flare class hierarchy, also courtesy Jeff Heer.
I'm continuting mbostocks's series of gists about pie charts.
This variation of a donut chart demonstrates how to add/remove slices or move between datasets of differing lengths with transitions. Clicking the radio buttons changes the displayed metric. Note how the new slice enters anticlockwise from the 'end' of the pie chart.