Hadley Wickham, creator of ggplot2, a R package for data plotting and visualization using R, posted slides, data and code of two short courses on the web. There are 5 sets of slides, covering the following topics:
- Introduction to ggplot2
- Graphics for large data
- ggplot2 theory
- Data manipulation and transformation
- Polishing your plots
You can find the slides and data here. Make sure to check out the ggplot2 site itself too. It provides an excellent reference manual, listing all types of graphs with links to more extensive documentation.