Area 51
Stack Exchange Network staging zone, where users come together to build new Q&A sites
Physics
Q&A for active researchers, academics and students of physics
Android Enthusiasts
Q&A for enthusiasts and power users of the Android operating system
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems.
Stack Overflow
Q&A for professional and enthusiast programmers
Photography
Q&A for professional, enthusiast and amateur photographers
Game Development
Q&A for professional and independent game developers
Server Fault
Q&A for professional system and network administrators
Electrical Engineering
Q&A for electronics and electrical engineering professionals, students, and enthusiasts
Database Administrators
Q&A for database professionals who wish to improve their database skills and learn from others in the community
Cross Validated
Q&A for statisticians, data analysts, data miners and data visualization experts
Programmers
Q&A for professional programmers interested in conceptual questions about software development
Mathematics
Q&A for people studying math at any level and professionals in related fields
User Experience
Q&A for user experience researchers and experts
TeX - LaTeX
Q&A for users of TeX, LaTeX, ConTeXt, and related typesetting systems
Cognitive Sciences
Q&A for practitioners, researchers, and students in cognitive science, psychology, neuroscience, and psychiatry
Parenting
Q&A for parents, grandparents, nannies and others with a parenting role
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
Programming Puzzles & Code Golf
Q&A for programming puzzle enthusiasts and code golfers
Graphic Design
Q&A for professional graphic designers and non-designers trying to do their own graphic design
Quantitative Finance
Q&A for finance professionals and academics
Personal Productivity
Q&A for people wanting to improve their personal productivity
Computational Science
Q&A for scientists using computers to solve scientific problems
Physical Fitness
Q&A for physical fitness professionals, athletes, trainers, and those providing health-related needs
Answers OnStartups
Q&A for entrepreneurs looking to start or run a new business