Ask Different
Q&A for power users of Apple hardware and software
TeX - LaTeX
Q&A for users of TeX, LaTeX, ConTeXt, and related typesetting systems
Stack Overflow
Q&A for professional and enthusiast programmers
Mathematics
Q&A for people studying math at any level and professionals in related fields
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems
Cross Validated
Q&A for people interested in statistics, machine learning, data analysis, data mining, and data visualization
Super User
Q&A for computer enthusiasts and power users
English Language Learners
Q&A for speakers of other languages learning English
Computer Science
Q&A for students, researchers and practitioners of computer science
Arqade
Q&A for passionate videogamers on all platforms
Emacs
Q&A for those using, extending or developing Emacs
English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
Academia
Q&A for academics and those enrolled in higher education
Vi and Vim
Q&A for people using the vi and Vim families of text editors
Chinese Language
Q&A for students, teachers, and linguists wanting to discuss the finer points of the Chinese language
Language Learning
Q&A for students, teachers, polyglots, and anyone interested in the techniques of second-language acquisition