Pie charts, pie charts, and more pie charts. Everything related to data visualization can be found here: useful techniques, inspiration, frameworks, and thought provoking ideas.
The Present Beyond Measure® Show by Lea Pica
Flowingdata - A lot of good examples of visualization for inspiration
Gapminder - Visualization with charts and physical objects
PICA Protocol: A Visualization Prescription for Impactful Data Storytelling - Whiteboard Friday episode summarizing the PICA Protocol by Lea Pica (Video)
Business Intelligence and Data Visualization tools compared - Comparison of Tableau, Looker, Mode Analytics, Periscope and Chart.io by Stephen Levin