I've been using R regularly, for W-NOMINATE and for other things. It's a free, open source programming language created to perform statistical analyses, and it's very popular in some academic circles.

I never got a good introduction to it, though, so I'm excited to see that Coursera is offering a course, Computing for Data Analysis, which is all about using R. I will definitely be taking this, and I recommend it to anyone else who does statistical analyses on a regular basis.