Area 51
Stack Exchange Network staging zone, where users come together to build new Q&A sites
Role-playing Games
Q&A for gamemasters and players of tabletop, paper-and-pencil role-playing games
Programmers
Q&A for professional programmers interested in conceptual questions about software development
Ask Different
Q&A for power users of Apple hardware and software
User Experience
Q&A for user experience researchers and experts
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems.
Theoretical Computer Science
Q&A for theoretical computer scientists and researchers in related fields
Bicycles
Q&A for people who build and repair bicycles, people who train cycling, or commute on bicycles
Physics
Q&A for active researchers, academics and students of physics
Server Fault
Q&A for professional system and network administrators
Electrical Engineering
Q&A for electronics and electrical engineering professionals, students, and enthusiasts
Android Enthusiasts
Q&A for enthusiasts and power users of the Android operating system
Stack Overflow
Q&A for professional and enthusiast programmers
Game Development
Q&A for professional and independent game developers
Mathematics
Q&A for people studying math at any level and professionals in related fields
Meta Stack Overflow
Q&A for meta-discussion of the Stack Exchange family of Q&A websites
TeX - LaTeX
Q&A for users of TeX, LaTeX, ConTeXt, and related typesetting systems
English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
German Language & Usage
Q&A for speakers of German wanting to discuss the finer points of the language and translation
Audio-Video Production
Q&A for engineers, producers, editors, and enthusiasts spanning the fields of audio, video, and media creation
Software Quality Assurance & Testing
Q&A for software quality control experts, automation engineers, and software testers
Personal Finance & Money
Q&A for people who want to be financially literate
Answers OnStartups
Q&A for entrepreneurs looking to start or run a new business
Programming Puzzles & Code Golf
Q&A for programming puzzle enthusiasts and code golfers