Working with the Puget Sound Regional Council, I've modified my acs package for R to allow users to download data directly from the Census ACS API. See http://eglenn.scripts.mit.edu/citystate/2013/02/major-improvements-to-acs-r-sneak-peak-at-version-1-0/ for more info and user guide.
Features and improvements include:
* The package is now capable of downloading data directly from the new Census American Community Survey API and importing into R (with proper statistical treatment of estimates and error, variable and geographic relabeling, and more), all through a single “acs.fetch()” function;
* The package includes a new “geo.make()” function to allow users to create their own custom geographies for organize and download data; and
* The package provides two special “lookup” tools to help filter through all the existing Census geographies (with the “geo.lookup()” function) and tables (with the “acs.lookup()” function) to find exactly what they want. These functions return new R “lookup” objects which can be saved, manipulated, and passed to acs.fetch() for downloading data.
(Still beta, but getting close -- any help/testing appreciated.)