What documentation exists for R?

Chapter 5: R Add-On Packages 76
5.5 How can I create an R package?
A package consists of a subdirectory containing the files ‘DESCRIPTION’ and ‘INDEX’, and the
subdirectories ‘R’, ‘data’, ‘demo’, ‘exec’, ‘inst’, ‘man’, ‘src’, and ‘tests’ (some of which can
be missing). Optionally the package can also contain script files ‘configure’ and ‘cleanup’
which are executed before and after installation.
See section “Creating R packages” in Writing R Extensions, for details.
R version 1.3.0 has added the function package.skeleton() which will set up directories,
save data and code, and create skeleton help files for a set of R functions and datasets.
See Section 2.10 [What is CRAN?], page 10, for information on uploading a package to
CRAN.
5.6 How can I contribute to R?
R is in active development and there is always a risk of bugs creeping in. Also, the developers
do not have access to all possible machines capable of running R. So, simply using it and
communicating problems is certainly of great value.
One place where functionality is still missing is the modeling software as described in
“Statistical Models in S” (see Section 3.1 [What is S?], page 12); some of the nonlinear
modeling code is not there yet.
The R Developer Page acts as an intermediate repository for more or less finalized ideas
and plans for the R statistical system. It contains (pointers to) TODO lists, RFCs, various
other writeups, ideas lists, and CVS miscellanea.
Many (more) of the packages available at the Statlib S Repository might be worth porting
to R.
If you are interested in working on any of these projects, please notify Kurt Hornik.