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 begins the course by discussing a number of resources he's posted on his GitHub account. These include Tributary.io, Bl.ocks.org, and the use of reddit.com's data API. Both Tributary and Blocks are great places to post code when experimenting with D3. Ian also demonstrates the visualization project being built throughout this course