Area 51
Stack Exchange Network staging zone, where users come together to build new Q&A sites
Meta Stack Overflow
Q&A for meta-discussion of the Stack Exchange family of Q&A websites
Programmers
Q&A for professional programmers interested in conceptual questions about software development
German Language & Usage
Q&A for speakers of German wanting to discuss the finer points of the language and translation
Electrical Engineering
Q&A for electronics and electrical engineering professionals, students, and enthusiasts
Photography
Q&A for professional, enthusiast and amateur photographers
Ask Different
Q&A for power users of Apple hardware and software
Computer Science
Q&A for students, researchers and practitioners of computer science
Server Fault
Q&A for professional system and network administrators
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems.
Mathematics
Q&A for people studying math at any level and professionals in related fields
English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
Physics
Q&A for active researchers, academics and students of physics
Theoretical Computer Science
Q&A for theoretical computer scientists and researchers in related fields
Web Applications
Q&A for power users of web applications
Stack Apps
Q&A for apps, scripts, and development with the Stack Exchange API
Geographic Information Systems
Q&A for cartographers, geographers and GIS professionals
TeX - LaTeX
Q&A for users of TeX, LaTeX, ConTeXt, and related typesetting systems
Signal Processing
Q&A for practitioners of the art and science of signal, image and video processing
Personal Finance & Money
Q&A for people who want to be financially literate
Cryptography
Q&A for software developers, mathematicians and others interested in cryptography