• School of Data Online Resources (schoolofdata.org)
• Open Data Cookbook Wiki (opendatacookbook.net)
• The Data Journalism Handbook (Google Doc)
• Intro to Linked Open Data for Visualization (datavisualization.ch)
• Exploring Data Flow with Google Refine and CRM (timdavies.org.uk)
• Free Data Visualisation Tools (guardian.co.uk)
• 30 Simple Tools For Data Visualization (fastcodesign.com)
• 8 cool tools for data analysis and visualization (cio.com.au)
• Top 20 data visualization tools (netmagazine.com)
• The Seven Steps of Visualizing Data (ischool.syr.edu)
• Open Government data workshop (github.com)
• WTFViz.net (how NOT to visualize!)

Don't miss our own Quickstart Guide.