There is an increasing set of R packages for interacting with the web from R, whether it be the low level tools to interact with the web via http (see RCurl and httr), parsing data from the web (like RJSONIO and XML), or wrappers to web APIs that provide data (like twitteR). Most of you probably know about CRAN Task Views that aggregate information about R packages and functions on a particular subject area into a simple web page.