R

R language is implementation of S language, implemented in New Zealand. It is that simple. So, if you know S then R will be really easy for you and it runs even on Play Station 3! If actually anyone cares.

R works in memory, so loading bigger data can be an issue. That is good to consider before using R for manipulating big data. But there is benefit, there is about 4000 packages you can use. For small data, of course.

R books: http://www.r-project.org/doc/bib/R-books.html

Interactive learning package: http://swirlstats.com