DiRT - Digital Research Tools Wiki

Image via Wikipedia

DiRT - Plant seeds. Grow ideas. - I like the name and the garden theme. What I especially like, however, is the treasure chest of information about data visualization tools. An absolutely outstanding resource in a wiki format.

FlowingData - Strength in Numbers

FlowingData is a website with a wealth of information about data visualization.

To get a good idea of how much is there, check out the Archive.

Also, it's worth it to visit the FlowingData Forums.