R Books
Learn R and Statistics
Art of R Programming
A straightforward introduction to the R language. No prior statistical knowledge is needed.
R in a Nutshell
Another introduction to R book. Learn to program R and use it to solve data analysis problems.
Introductory Statistics with R
This concise book interweaves statistics and R together. It's for developers who need to brush up on their statistics.
Statistics in a Nutshell
Not about the R language, but it's a great overview of the statistical tests used heavily in R.
Doing Bayesian Data Analysis
Teaches the Bayesian branch of statistics. Prerequisite of algebra and basic calculus required.
Data Mining with R
Written in a case study format, this textbook does not assume prior knowledge of R or statistics.
R Graphics
A visualization is worth its weight in gold. R has great support for creating graphics. Recently updated to include a chapter on ggplot2.