Stack Overflow
Q&A for professional and enthusiast programmers
Mathematics
Q&A for people studying math at any level and professionals in related fields
Super User
Q&A for computer enthusiasts and power users
Ask Ubuntu
Q&A for Ubuntu users and developers
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems
Web Applications
Q&A for power users of web applications
The Great Outdoors
Q&A for people who love being outdoors enjoying nature and wilderness, and learning about the required skills and equipment
Freelancing
Q&A for self-employed and freelance workers
The Workplace
Q&A for members of the workforce navigating the professional setting
Software Engineering
Q&A for professionals, academics, and students working within the systems development life cycle
Information Security
Q&A for information security professionals
Signal Processing
Q&A for practitioners of the art and science of signal, image and video processing
Biology
Q&A for biology researchers, academics, and students
English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
Game Development
Q&A for professional and independent game developers
Personal Finance & Money
Q&A for people who want to be financially literate
Code Review
Q&A for peer programmer code reviews
Music: Practice & Theory
Q&A for musicians, students, and enthusiasts
Travel
Q&A for road warriors and seasoned travelers
Academia
Q&A for academics and those enrolled in higher education