Cheat SheetsDan's R Cheat Sheet: a 2page summary of the functions I use the most.Cheatsheets by RStudio: infopacked 2page guides for graphing, data wrangling, markdown, etc.
Reference WebsitesQuickR: an excellent searchable reference guideCookbook for R: cookbookstyle howto wiki, particularly useful for experimental psychology
Penn R study group: detailed reference in the form of tutorial notes
ggplot2: documentation website for our main graphics tool
A great ggplot2 workshop.
A chart chooser: simple examples of many different kinds of ggplot graphs.
A nice guide to themes.
Quick reference guide, including handy chart of named colors. Matlab/R Reference guide: A handy reference for both R and Matlab (our other main analytical tool) R style guides: Hadley Wickham's Style Guide
Google's R Style Guide
Learning R
CommunityRlangPsychR R Bloggers: A blog aggregator pulling together posts from over 140 bloggers who write about R in English StackOverflow  R: A great community Q & A site. If you have a problem, they can usually help you.
BooksR in a Nutshell by Joseph AdlerR for SAS and SPSS Users by Robert Muenchen Analyzing Linguistic Data by Harald Baayen ggplot2: part of the Use R! series of focused guide books Books that teach statistics and R together:
Learning Statistics with R by Daniel Navarro (ebook is free!)
Discovering Statistics Using R by Andy Field, Jeremy Miles, & Zoe Field
