Mathematician (Ph.D. in combinatorics, graph theory, posets). Undergraduate physics major as well, although the experience taught me that I'm not a physicist. Still, I enjoy physics and engineering recreationally. I'm not much interested in "wet" sciences (chemistry and biology are prime examples). Too messy for me.
Highly experienced computer programmer (Java, Python, PowerBuilder, Fortran, APL). I'm not going to say how old I am, but I wrote and ran my first programs on an IBM computer in 1965. It wasn't a micro. :-)
Highly experienced Linux system administrator (shell scripting, configuration of most widely used daemons).
Interest and some experience in optimization (linear/mixed integer programming), mathematical modeling.
Chess enthusiast, although I'm basically a fish.
Oh, and I'm a retired Marine A-4 pilot.