Stack Overflow
Q&A for professional and enthusiast programmers
Photography
Q&A for professional, enthusiast and amateur photographers
Android Enthusiasts
Q&A for enthusiasts and power users of the Android operating system
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems.
Theoretical Computer Science
Q&A for theoretical computer scientists and researchers in related fields
Physics
Q&A for active researchers, academics and students of physics
Super User
Q&A for computer enthusiasts and power users
Programmers
Q&A for professional programmers interested in conceptual questions about software development
Mathematics
Q&A for people studying math at any level and professionals in related fields
TeX - LaTeX
Q&A for users of TeX, LaTeX, ConTeXt, and related typesetting systems
English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
Philosophy
Q&A for those interested in logical reasoning
Academia
Q&A for academics and those enrolled in higher education
Cryptography
Q&A for software developers, mathematicians and others interested in cryptography