TeX - LaTeX
Q&A for users of TeX, LaTeX, ConTeXt, and related typesetting systems
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems
Super User
Q&A for computer enthusiasts and power users
Stack Overflow
Q&A for professional and enthusiast programmers
Mathematica
Q&A for users of Wolfram Mathematica
Ask Ubuntu
Q&A for Ubuntu users and developers
Mathematics
Q&A for people studying math at any level and professionals in related fields
Vi and Vim
Q&A for people using the vi and Vim families of text editors
History
Q&A for historians and history buffs
Physics
Q&A for active researchers, academics and students of physics
Reverse Engineering
Q&A for researchers and developers who explore the principles of a system through analysis of its structure, function, and operation
Biology
Q&A for biology researchers, academics, and students
Signal Processing
Q&A for practitioners of the art and science of signal, image and video processing
Server Fault
Q&A for system and network administrators
Chemistry
Q&A for scientists, academics, teachers, and students in the field of chemistry
Software Engineering
Q&A for professionals, academics, and students working within the systems development life cycle
English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
Cross Validated
Q&A for people interested in statistics, machine learning, data analysis, data mining, and data visualization
Ask Different
Q&A for power users of Apple hardware and software