What documentation exists for R?

Chapter 5: R Add-On Packages 61
treeglia Stem analysis functions for volume increment and carbon uptake assessment
from tree-rings.
trimcluster
Cluster analysis with trimming.
trip Spatial analysis of animal track data.
tripack A constrained two-dimensional Delaunay triangulation package.
truncgof Goodness-of-fit tests allowing for left truncated data.
trust Local optimization using two derivatives and trust regions.
tsDyn Time series analysis based on dynamical systems theory.
tseries Package for time series analysis with emphasis on non-linear modelling.
tseriesChaos
Routines for the analysis of non-linear time series.
tsfa Time Series Factor Analysis.
tuneR Collection of tools to analyze music, handle wave files, transcription, etc.
tutoR Student-friendly package to mask common functions.
twang Toolkit for Weighting and Analysis of Nonequivalent Groups.
tweedie Maximum likelihood computations for Tweedie exponential family models.
udunits Interface to Unidata’s routines to convert units.
ump Uniformly Most Powerful tests.
unbalhaar Function estimation via Unbalanced Haar wavelets.
untb Ecological drift under the UNTB (Unified Neutral Theory of Biodiversity).
urca Unit root and cointegration tests for time series data.
urn Functions for sampling without replacement (simulated urns).
uroot Unit root tests and graphics for seasonal time series.
vabayelMix
Variational Bayesian mixture model.
varSelRF Variable selection using random forests.
vardiag Interactive variogram diagnostics.
varmixt Mixture model on the variance for the analysis of gene expression data.
vars VAR modeling.
vcd Functions and data sets based on the book “Visualizing Categorical Data” by
Michael Friendly.
vegan Various help functions for vegetation scientists and community ecologists.
verification
Utilities for verification of discrete and probabilistic forecasts.