UCLA Statistics has a pretty extensive list of resources on how to use R and GRASS. For those unfamiliar, R is a programming language and environment for statistical computing and graphics. GRASS is an open source geographic information system (GIS). And of course, both are completely free and completely useful.
Useful Stat Resources for R and GRASS
Watching the growth of Walmart – now with 100% more Sam’s Club
The ever so popular Walmart growth map gets an update, and yes, it still looks like a wildfire. Sam’s Club follows soon after, although not nearly as vigorously.