Python

Till recently my explorations of Python had begun and ended with typing 2+2. Then I stumbled across this arxiv.org compilation of lecture notes, where the author uses python code snippets to teach. I also had noticed, for example, that the Naval Observatory provides software now in three flavors: Fortran, C, and Python. So the recent extensive publicity about Python in the AMS literature was just the final nudge to explore more.
While reading about previous suggestions by atmospheric scientists for installing Python on a Mac, I got off on a tangent by switching to a new package manager. Having used MacPorts awhile back, I've quickly learned now to enjoy Homebrew. I wasn't exactly sure about the next steps following installation of a Homebrewed Python, but fortunately this programmer

brew tap samueljohn/python

recently added supplemental Homebrew formulae for installing numpy, scipy and matplotib. His formulae worked.
My impression is that someone starting out today might never need to learn another programming language other than Python.