Visualisation :: Choosing a chart
The Graphic Continuum. Poster taxonomy of different types of charts, and how they all relate to each other.
A Taxonomy of Data Visualization
A Tour through the Visualization Zoo by Jeffrey Heer, Michael Bostock, and Vadim Ogievetsky
Chart chooser diagram (classical charts)
Data Visualization: Modern Approaches
Designing Effective Tables and Graphs by Stephen Few, with a Graph Selection Matrix
Graphics cheat sheet (pdf)
Patterns for Information Visualization
Types of information visualisation
Introduction to Data Visualization: Visualization Types
The data visualisation catalogue, by function
Treevis.net - A Visual Bibliography of Tree Visualization 2.0 by Hans-Jörg Schulz
The TimeViz Browser - A Visual Survey of Visualization Techniques for Time-Oriented Data
Gallery of Data Visualisation, covering bright ideas, graphical excellence and visual delights
Head to pinterest and search for boards with visualisation in their name. For instance, my board
A Survey on Information Visualization: Recent Advances and Challenges