I swear I remember this diagram from the GNU Arch days.
I think this would be pretty easy to do with gpplot2, but Portfolio looks like its worth checking out too.
Neal Caren's (UNC) data scraping/processing tutorial. Potentially a useful teaching/learning resource?
Good vim tricks and tutorial page by Jonathan McPherson.
A somewhat hard-to-find-but-useful set of ggplot2 examples buried on Hadley Wickham's site.
Simple intro to graphic programming in Python. From pfctdayelise.