Currently, the CRAN package repository features 6561 available packages.
Table of available packages, sorted by date of publication
Table of available packages, sorted by name
Please type help("INSTALL") or help("install.packages") in R for information on how to install packages from this repository. The manual R Installation and Administration (also contained in the R base sources) explains the process in detail.
CRAN Task Views allow you to browse packages by topic and provide tools to automatically install all packages for special areas of interest. Currently, 33 views are available.
All packages are tested regularly on machines running Debian GNU/Linux, Fedora and Solaris. Packages are also checked under OS X and Windows, but typically only on the day the package appears on CRAN.
The results are summarized in the check summary (some timings are also available). Additional details for Windows checking and building can be found in the Windows check summary.
The manual Writing R Extensions (also contained in the R base sources) explains how to write new packages and how to contribute them to CRAN.
The manual CRAN Repository Policy [PDF] describes the policies in place for the CRAN package repository.