Interactive Data Visualization for the Web by Scott Murray.
From the webpage:
This online version of Interactive Data Visualization for the Web includes 44 examples that will show you how to best represent your interactive data. For instance, you’ll learn how to create this simple force layout with 10 nodes and 12 edges. Click and drag the nodes below to see the diagram react.
When you follow the link to the O’Reilly site, just ignore the eBook pricing and go directly to “read online.”
Much crisper than the early version I mention at: Interactive Data Visualization for the Web [D3].
I first saw this in a tweet by Kirk Borne.