As an occupation, I'm a mathematical physicist, studying string theory and quantum field theory.
I've developed as a hobby a few Cocoa (Touch) apps. The largest one so far is spires.app, which manages articles and metadata downloaded from the arXiv eprint server, the inspire database, and the journal websites.
I'm also interested in many other things, which is why I ask questions in various StackExchange sites ...
Q&A for professional and enthusiast programmers
Q&A for professional mathematicians
Q&A for active researchers, academics and students of physics
Q&A for power users of Apple hardware and software
Q&A for linguists, etymologists, and serious English language enthusiasts
Q&A for users of TeX, LaTeX, ConTeXt, and related typesetting systems
Q&A for computer enthusiasts and power users
Q&A for professional and amateur chefs
Q&A for students, teachers, and linguists wanting to discuss the finer points of the Japanese language
Q&A for people studying math at any level and professionals in related fields
Stack Exchange Network staging zone, where users come together to build new Q&A sites
Q&A for committed Christians, experts in Christianity and those interested in learning more
Q&A for students, teachers, and linguists wanting to discuss the finer points of the French language
Q&A for professional linguists and others with an interest in linguistic research and theory
Q&A for meta-discussion of the Stack Exchange family of Q&A websites
Q&A for system and network administrators
Q&A for Graphic Design professionals, students, and enthusiasts
Q&A for professional programmers interested in conceptual questions about software development
Q&A for users of Mathematica
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems