Mod parent up please. The Scientific Python stack (numpy, scipy, pandas, etc.) with it's iPython Notebook interface (in the style of Mathematica) is rapidly taking the world by storm, both in the sciences as well as Big Data Analytics and "Data Science".
If you like software toys, or ever use a calculator, go get yourself the free Anaconda scientific python distribution (Win/Mac/Linux) from Continuum and try out the iPython Notebook. Seriously this is an out-of-the-box computing tool that is AMAZING and can do practically anything. Anaconda is built on the Conda package manager which makes installing any and all bits and pieces you need for any of the popular Python packages completely effortless.
The existence of these tools also makes Python absolutely the best "programming" language to learn, even if you only use it for scripting/invoking all the existing libraries that exist. Also Python is available as a scripting language built into many software packages (Blender etc.) which makes it a tool/skill that just keeps on giving.
R is fine, and currently very popular, but it's also a one-trick-pony when compared to the thundering herd of functionality available on top of Python. You can even invoke R from within an iPython Notebook and pass DataFrames back and forth between R and pandas for example.
I used to love calculators (back when calculator was spelled H-P rather than T-I) but apart from the standardized testing requirement, and the fun of hacking on hand-held devices, it's just silly to use one any more.
https://store.continuum.io/csh... (free, open source)
http://nbviewer.ipython.org/ (great way to share Notebooks)
http://computableapp.com/ (the SciPy stack for iPads
http://omz-software.com/python... (Great iOS Python environment)
http://numfocus.org/projects/i... (Foundation supporting the core SciPy stack components)
http://pythontutor.com/ (This is just too cool)