This used to be the front page of “Impatient R” which at the time was called “Some hints for the R beginner”.
“Impatient R” provides a brief grounding in the basics of using R.
Try R is a fun way of learning some R.
There is a set of two-minute videos called R twotorials.
R is a good way to avoid problems with spreadsheets.
See also “Why use the R language?”
R and finance
R is used a lot in finance, and that use is growing. There are two task views that are pertinent:
The R language category of the Portfolio Probe blog has examples of R being used in the context of quantitative finance.
Other R resources
The R-bloggers site aggregates blog posts about R.
There are R user groups around the world.