For some reason I’ve ran across several open source stats tools that I had never heard of before in the last week:

• PSPP, an open source replacement for SPSS.
• JASP, a friendly GUI-based stats package powered by R.
• jamovi, another friendly GUI-based, R-powered stats package.
• Radiant, yet another front-end for R. This one is more focused on “business intelligence” (read: visualization and exploration) than stats, but it does have a fair amount of stats functionality.

I keep track of these sorts of things on the epidemiology tools page on my website.