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 active researchers, academics and students of physics
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
Stack Exchange Network staging zone, where users come together to build new Q&A sites
Q&A for people studying math at any level and professionals in related fields
Q&A for students, teachers, and linguists wanting to discuss the finer points of the French language
Q&A for committed Christians, experts in Christianity and those interested in learning more
Q&A for professional programmers interested in conceptual questions about software development
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems.
Q&A for users of Mathematica
Q&A for meta-discussion of the Stack Exchange family of Q&A websites
Q&A for power users of Apple hardware and software
Q&A for professional system and network administrators
Q&A for professional graphic designers and non-designers trying to do their own graphic design