Here's a list of resources that I would suggest:
Tufte's books are really excellent, although my favorite is actually his second book: Envisioning Information. Separately, I always found the periodic table of visualization methods to be entertaining. Ross Ihaka also taught a course on this subject in the past.
For R, learn ggplot2. The learnr.wordpress.com blog is an excellent resource for this. You might consider the ggplot book and the original Grammar of Graphics book.
Here's another useful article from the same site that you linked in your question: Data Visualization: Modern Approaches.
Some good blogs on the subject:
- http://www.informationisbeautiful.net/
- http://flowingdata.com/
In some cases, you might want to do your data manipulation in R, but create the visualization with another tool (see, for instance, this list). Here are some of the best tools that I have found over the years:
- Processing
- Prefuse
- Protovis
Lastly, an interesting open visualization platform is available at many eyes.
