It has repeatedly come to my attention that people don't understand how and when to use pie charts. In general, pie charts are an inferior visualization; you almost always want a bar chart or a table or a list instead. There are very specific situations when pie charts are a reasonable choice, and there are some rules you should always follow ( Read more... )

This is one of the more visually interesting Google Maps mashups I've seen: OnionMap, a sort of tourist guide map (to popular tourist cities only), highlighting points of interest based on category. They don't appear to be very far along, but you definitely get the idea from what they have so far.

In addition to the amusing title, the methodology is nice (diagrams included!), though no better than other solutions I've seen. This particular line of research is surprisingly still fairly unexplored.

Social networking for zebras