The R online training site DataCamp has created an infographic comparing R, SAS and SPSS. Provocatively titled "Statistical Language Wars", the infographic compares the history, purpose, ease of learning, popularity and marketability of skills in each of the three systems. Here's a small detail (click for the full chart):
The chart also includes a couple of examples of companies using each system; you can find a longer list of companies using R at the Community section of the Revolution Analytics website.
DataCamp: Statistical Language Wars: The Infograph