Simile, a project MIT, has created several open source tools for visualizing data on the web. The interfaces are clean and free of unnecessary decoration, and the AJAX interaction encourages exploration and questioning. These are an excellent addition to the information design toolbox.
Timeplot is a “DHTML-based AJAXy widget for plotting time series and overlay time-based [...]
Smashing Magazine compiled a long list of modern approaches to visualizing data, including mind maps, charts, maps, bubble charts, histograms and more. It’s an excellent reference for gathering ideas and challenging assumptions about how to present data and relationships.
Example below from visualcomplexity.com.
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Juan C. Duersteler writes that Mendeleev’s periodic table is brilliant information visualization …
When the Russian chemist Dmitri Mendeleev published the first version of his Periodic Table of the Elements in 1869 he couldn’t imagine that it would become in due time one of the most outstanding information visualisations and that many fields would use it [...]