With the plethora of R packages available finding the ‘right tool for the job’ can often take a little while.
A good place to start are the ‘Task Views’ pages on the CRAN website which detail the current tools available for different areas of statistical analysis. For instance there is a Task View page on tools for Bayesian Inference in R, another on tools for the analysis of Spatial Data in R and another on ‘High-Performance and Parallel Computing with R’.
Some packages will have ‘Vignettes’ (documentation additional to their manuals) to be found on their associated CRAN pages.
For instance the R package ‘filehash’ has an associated Vignette which explains the concept of a ‘key-value style database’ which it utilises to facilitate interacting with data larger than will fit in the physical memory (RAM).