I'm interested in learning R on the cheap. What's the best free resource/book/tutorial for learning R?
Some useful R links (find out the link that suits you):
Intro:

for R basics http://cran.r-project.org/doc/contrib/usingR.pdf
for data manipulation http://had.co.nz/plyr/plyr-intro-090510.pdf
http://portal.stats.ox.ac.uk/userdata/ruth/APTS2012/APTS.html
Interactive intro to R programming language https://www.datacamp.com/courses/introduction-to-r
Application focused R tutorial https://www.teamleada.com/tutorials/introduction-to-statistical-programming-in-r
In-browser learning for R http://tryr.codeschool.com/

with a focus on economics:

lecture notes with R code http://www.econ.uiuc.edu/~econ472/e-Tutorial.html
A brief guide to R and Economics http://people.su.se/~ma/R_intro/R_intro.pdf

Graphics: plots, maps, etc.:

tutorial with info on plots http://cran.r-project.org/doc/contrib/Rossiter-RIntro-ITC.pdf
a graph gallery of R plots and charts with supporting code http://addictedtor.free.fr/graphiques/
A tutorial for Lattice http://osiris.sunderland.ac.uk/~cs0her/Statistics/UsingLatticeGraphicsInR.htm
Ggplot R graphics http://had.co.nz/ggplot2/
Ggplot Vs Lattice @ http://had.co.nz/ggplot/vs-lattice.html
Multiple tutorials for using ggplot2 and Lattice http://learnr.wordpress.com/tag/ggplot2/
Google Charts with R http://www.iq.harvard.edu/blog/sss/archives/2008/04/google_charts_f_1.shtml
Introduction to using RGoogleMaps @ http://cran.r-project.org/web/packages/RgoogleMaps/vignettes/RgoogleMaps-intro.pdf
Thematic Maps with R https://stackoverflow.com/questions/1260965/developing-geographic-thematic-maps-with-r
geographic maps in R http://smartdatacollective.com/Home/22052

GUIs:

Poor Man GUI for R http://wiener.math.csi.cuny.edu/pmg/
R Commander is a robust GUI for R http://socserv.mcmaster.ca/jfox/Misc/Rcmdr/installation-notes.html
JGR is a Java-based GUI for R http://jgr.markushelbig.org/Screenshots.html

Time series & finance:

a good beginner’s tutorial for Time Series http://www.stat.pitt.edu/stoffer/tsa2/index.html

Interesting time series packages in R http://robjhyndman.com/software

advanced time series in R http://www.wise.xmu.edu.cn/2007summerworkshop/download/Advanced%20Topics%20in%20Time%20Series%20Econometrics%20Using%20R1_ZongwuCAI.pdf

provides a great analysis and visualization framework for quantitative trading http://www.quantmod.com/

Guide to Credit Scoring using R http://cran.r-project.org/doc/contrib/Sharma-CreditScoring.pdf

an Open Source framework for Financial Analysis http://www.rmetrics.org/


Data / text mining:

A Data Mining tool in R http://rattle.togaware.com/
An online e-book for Data Mining with R http://www.liaad.up.pt/~ltorgo/DataMiningWithR/
Introduction to the Text Mining package in R http://cran.r-project.org/web/packages/tm/vignettes/tm.pdf

Other statistical techniques:

Quick-R http://www.statmethods.net/
annotated guides for a variety of models http://www.ats.ucla.edu/stat/r/dae/default.htm
Social Network Analysis http://www.r-project.org/conferences/useR-2008/slides/Bojanowski.pdf

Editors:

Komodo Edit R editor http://www.sciviews.org/SciViews-K/index.html
Tinn-R makes for a good R editor http://www.sciviews.org/Tinn-R/
An Eclipse plugin for R @ http://www.walware.de/goto/statet
Instructions to install StatET in Eclipse http://www.splusbook.com/Rintro/R_Eclipse_StatET.pdf
RStudio http://rstudio.org/
Emacs Speaks Statistics, a statistical language package for Emacs http://ess.r-project.org/

Interfacing w/ other languages / software:

to embed R data frames in Excel via multiple approaches http://learnr.wordpress.com/2009/10/06/export-data-frames-to-multi-worksheet-excel-file/
provides a tool to make R usable from Excel http://www.statconn.com/
Connect to MySQL from R http://erikvold.com/blog/index.cfm/2008/8/20/how-to-connect-to-mysql-with-r-in-wndows-using-rmysql
info about pulling data from SAS, STATA, SPSS, etc. http://www.statmethods.net/input/importingdata.html
Latex http://www.stat.uni-muenchen.de/~leisch/Sweave/
R2HTML http://www.feferraz.net/en/P/R2HTML

Blogs, newsletters, etc.:

A very informative blog http://blog.revolutionanalytics.com/
A blog aggregator for posts about R  http://www.r-bloggers.com/
R mailing lists  http://www.r-project.org/mail.html
R newsletter (old)  http://cran.r-project.org/doc/Rnews/
R journal (current)  http://journal.r-project.org/

Other / uncategorized: (as of yet)

Web Scraping in R http://www.programmingr.com/content/webscraping-using-readlines-and-rcurl
a very interesting list of packages that is seriously worth a look http://www.omegahat.org/
Commercial versions of R @ http://www.revolutionanalytics.com/
Red R for R tasks http://code.google.com/p/r-orange/
KNIME for R (worth a serious look) http://www.knime.org/introduction/screenshots
R Tutorial for Titanic https://statsguys.wordpress.com/

