I'm a computer engineering and computer science student.
My favorite languages are bash, C, C++, Python, Verilog, Perl, and Haskell, but of those I'm only fluent in the first 6. I'm also fluent in Matlab (well... GNU Octave, really), Java and VHDL. And I like Scala better than vanilla Java- except when it comes to the collections framework- because mixins.
LaTeX is also very fun, and I can use it wonderfully, but ``fluent'' implies I know a lot about the language constructs, which I don't, so I'm not.
If it's an operating system whose name is a registered Bell of AT&T trademark Corporation, or based on the aforementioned, I like it. Currently, using FreeBSD on my main machine. But I also quite like OSX. I know how to use Windows effectively, but that O/S is just too GUI-oriented to make me happy. And, no, Powershell doesn't solve the problem. If I wanted to write DCL, I'd be running VMS.
CentOS and Debian also float my dirigible quite nicely.