If you have an interest in visualizing data, then you should be visiting the site Flowing Data on a regular basis.  The author is Dr. Nathan Yau (PhD), and he provides fantastic examples of best practices, worst practices, and interesting new approaches to data visualization.  Also, his posts frequently involve the use of open data.

The image below is from an article in which he imports earthquake data from the USGS and maps it using R.  Click here to visit his site and read the article.  He provides code to replicate his data visualization using R, plus there are additional details about the project if you’d like to learn more or build your own earthquakes visualization.