I would also check out dplyr for data munging. Since most of the code in dplyr is written in C++ it is much faster than the munging capabilities you probably used when you were using R years ago.
We at RStudio are actually working on a hosted version of Shiny which may be of interest. We have modeled it after the Heroku model, but obviously very much tailored towards hosting R sessions. If you would like to be part of the early alpha please sign up here: http://shinyapps.io/ and we will reach out as soon as it is ready for some people to bang on it and give us feedback.