Some useful R links (State of the R)                                            http://had.co.nz/plyr/plyr-intro-090510.pdf  for data manipulation
http://www.stats.ox.ac.uk/~ruth/RCourse/Rcourse3.pdfhttp://cran.r-project.org/doc/contrib/usingR.pdf for R basics
http://www.ats.ucla.edu/stat/r/dae/default.htm with annotated outputs in R
http://cran.r-project.org/doc/contrib/Rossiter-RIntro-ITC.pdf tutorial with info on plots
http://www.statmethods.net/stats/regression.htmlhttp://www.rmetrics.org/ provides an Open Source framework for Financial Analysis.
http://www.econ.uiuc.edu/~econ472/e-Tutorial.html has lecture notes with R code
A brief guide to R and Economics http://people.su.se/~ma/R_intro/R_intro.pdfhttp://www.stat.pitt.edu/stoffer/tsa2/index.html has a good beginner’s tutorial for Time Series
http://www.quantmod.com/ provides a great analysis and visualization framework for quantitative trading
http://www.wise.xmu.edu.cn/2007summerworkshop/download/Advanced%20Topics%20in%20Time%20Series%20Econometrics%20Using%20R1_ZongwuCAI.pdf advanced time series in R
Interesting time series packages in R http://robjhyndman.com/software
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/
Advanced Statistics using R http://www.statmethods.net/advstats/index.html
Guide to Credit Scoring using R http://cran.r-project.org/doc/contrib/Sharma-CreditScoring.pdfhttp://addictedtor.free.fr/graphiques/ is a graph gallery of R plots and charts with supporting code
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/
Introduction to the Text Mining package in R http://cran.r-project.org/web/packages/tm/vignettes/tm.pdf
Social Network Analysis  http://www.r-project.org/conferences/useR-2008/slides/Bojanowski.pdf
Web Scraping in R http://www.programmingr.com/content/webscraping-using-readlines-and-rcurlhttp://learnr.wordpress.com/2009/10/06/export-data-frames-to-multi-worksheet-excel-file/ to embed R data frames in Excel via multiple approaches.
http://www.statconn.com/ provides a tool to make R usable from Excel
Connect to MySQL from R http://erikvold.com/blog/index.cfm/2008/8/20/how-to-connect-to-mysql-with-r-in-wndows-using-rmysqlhttp://www.statmethods.net/input/importingdata.html provides info about pulling data from SAS, STATA, SPSS, etc.
Thematic Maps with R http://stackoverflow.com/questions/1260965/developing-geographic-thematic-maps-with-rhttp://smartdatacollective.com/Home/22052 for geographic maps in R
Google Charts with R http://www.iq.harvard.edu/blog/sss/archives/2008/04/google_charts_f_1.shtml
Intro to using RGoogleMaps @ http://cran.r-project.org/web/packages/RgoogleMaps/vignettes/RgoogleMaps-intro.pdfhttp://www.stat.uni-muenchen.de/~leisch/Sweave/
R2HTML http://www.feferraz.net/en/P/R2HTML
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
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
Komodo Edit R editor http://www.sciviews.org/SciViews-K/index.htmlhttp://www.omegahat.org/ has a very interesting list of packages that is seriously worth a look
Commercial versions of R @ http://www.revolution-computing.com/
A very informative blog http://blog.revolution-computing.com/
Red R for R tasks http://code.google.com/p/r-orange/
KNIME  for R http://www.knime.org/introduction/screenshots and is worth a serious look.