User Experience
Q&A for user experience researchers and experts
Japanese Language & Usage
Q&A for students, teachers, and linguists wanting to discuss the finer points of the Japanese language
Area 51
Stack Exchange Network staging zone, where users come together to build new Q&A sites
Programmers
Q&A for professional programmers interested in conceptual questions about software development
The Workplace
Q&A for members of the workforce navigating the professional setting
Science Fiction & Fantasy
Q&A for science fiction and fantasy enthusiasts
Physics
Q&A for active researchers, academics and students of physics
Photography
Q&A for professional, enthusiast and amateur photographers
Role-playing Games
Q&A for gamemasters and players of tabletop, paper-and-pencil role-playing games
Mathematics
Q&A for people studying math at any level and professionals in related fields
Cross Validated
Q&A for statisticians, data analysts, data miners and data visualization experts
Game Development
Q&A for professional and independent game developers
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems.
English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
Web Applications
Q&A for power users of web applications
Ask Different
Q&A for power users of Apple hardware and software
Meta Stack Overflow
Q&A for meta-discussion of the Stack Exchange family of Q&A websites
Database Administrators
Q&A for database professionals who wish to improve their database skills and learn from others in the community
Server Fault
Q&A for professional system and network administrators
Chinese Language & Usage
Q&A for students, teachers, and linguists wanting to discuss the finer points of the Chinese language
Graphic Design
Q&A for professional graphic designers and non-designers trying to do their own graphic design
English Language Learners
Q&A for speakers of other languages learning English
Software Quality Assurance & Testing
Q&A for software quality control experts, automation engineers, and software testers
Audio-Video Production
Q&A for engineers, producers, editors, and enthusiasts spanning the fields of audio, video, and media creation
Writers
Q&A for authors, editors, reviewers, professional writers, and aspiring writers
Answers OnStartups
Q&A for entrepreneurs looking to start or run a new business
Parenting
Q&A for parents, grandparents, nannies and others with a parenting role
Personal Finance & Money
Q&A for people who want to be financially literate