Ian Johnson is the author of Tributary - an open source live-coding environment designed for prototyping data visualizations with D3. He also co-organizes the SF Bay Area d3 Meetup and makes educational D3 videos.
Bay Area D3 and Tributary
Ian ports the Brush code from Tributary into the application. During the port, he strips out any of the data calls and adjusts the sizing to be based on the chart's parameters.