Server Fault
Q&A for professional system and network administrators
Area 51
Stack Exchange Network staging zone, where users come together to build new Q&A sites
WordPress Answers
Q&A for WordPress developers and administrators
Android Enthusiasts
Q&A for enthusiasts and power users of the Android operating system
English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
Programmers
Q&A for professional programmers interested in conceptual questions about software development
Role-playing Games
Q&A for gamemasters and players of tabletop, paper-and-pencil role-playing games
User Experience
Q&A for user experience researchers and experts
Science Fiction & Fantasy
Q&A for science fiction and fantasy enthusiasts
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.
Web Applications
Q&A for power users of web applications
Database Administrators
Q&A for database professionals who wish to improve their database skills and learn from others in the community
Theoretical Computer Science
Q&A for theoretical computer scientists and researchers in related fields
Stack Overflow
Q&A for professional and enthusiast programmers
Academia
Q&A for academics and those enrolled in higher education
Genealogy & Family History
Q&A for expert genealogists and people interested in genealogy or family history
Raspberry Pi
Q&A for users and developers of hardware and software for Raspberry Pi
Answers OnStartups
Q&A for entrepreneurs looking to start or run a new business
Physical Fitness
Q&A for physical fitness professionals, athletes, trainers, and those providing health-related needs
The Workplace
Q&A for members of the workforce navigating the professional setting
English Language Learners
Q&A for speakers of other languages learning English
Personal Productivity
Q&A for people wanting to improve their personal productivity