Listing of classic R datasets used in various packages
Hadley Wickhams's GitHub page for his advanced R development courses. Includes useful material on advanced programming in R as well as package development.
Markdown package for the R statistical software environment. Handy for publishing R code (e.g. to Rpubs) and for integrating latex, comments and other text more seamlessly into code.
An example of R code that tests for a mediation relationship.
A somewhat hard-to-find-but-useful set of ggplot2 examples buried on Hadley Wickham's site.