Valve is giving away the Portal 2 soundtrack on the Portal website. You should go get it, for science. Portal 2 Soundtrack
An ebook, Think Stats: Probability and Statistics for Programmers, teaches statistics through hands on programming oriented exercises. You can find a data set used in the book here.
Microsoft Research just released Sho, a marriage of .NET and Python. I would try it out, but I need to upgrade before I can run it.
Courtesy of Jerry Pournelle, I found out today that Microsoft Mathematics 4.0 is now free. It used to be $20. I've never used it, so I have no idea of its utility versus other free applications that do the same thing, but we all like free. Microsoft
Is git. Mark Dominus has a talk with slides online that I found absolutely fascinating. John Wiegley has a more in-depth explanation of git for those who need to know the details.
Two free ebooks today. The first is Breaking the Law of Averages, an introductory statistics book that I recomment. Matt Briggs approaches the subject in a wholly modern way, relying on your computer to do the math, allowing the student to focus on the more important task of understanding what