BTW, aside from C, C++, Python, D, and Rust, what languages have do you (even if only a little bit)? I am specifically wondering if you are familiar with the Wirth languages (particularly Pascal, Modula-2, and Oberon), or the closely related Ada. While these sorts of languages are out of favor today, it is still worth knowing something about them.
Also, are you at all familiar with either Forth, Smalltalk, or Prolog? They take very different directions from conventional languages, and even a limited familiarity with them might be worth having.
As I've said before, my own interests mainly lie with Scheme, and one of the major advantages of Scheme is that the core language is very easy to learn in a short time, but at the same time it is an amazingly flexible and powerful language in several ways (though it has several problems as well, most of which relate to the rather minimalist standard library and the incompatibilities in the various implementations). You might want to take a few days to familiarize yourself with some Scheme implementation or dialect thereof (Racket is probably the most practical choice, since that seems to be the best supported lately) just to fill in the blanks on the topic a bit.
