Periodic Table of Visualization
This table is a must-see site for anyone who works creating visualizations. This website from visual-literacy.org has grouped visual methods into six categories (like Concept Visualization and Metaphor Visualization), and made it interactive so when you move your mouse over one of the specific methods it shows you an example.
This is a great resource to help inspire you to visualize your data in new ways. I find that I like trying to visualize the same data in a couple different ways to find out which works best at communicating the data to others. Ironically it's missing the visual method of laying out data into a periodic table!