Stack Overflow
Q&A for professional and enthusiast programmers
Meta Stack Overflow
Q&A for meta-discussion of the Stack Exchange family of Q&A websites
Ask Different
Q&A for power users of Apple hardware and software
Cryptography
Q&A for software developers, mathematicians and others interested in cryptography
Android Enthusiasts
Q&A for enthusiasts and power users of the Android operating system
Area 51
Stack Exchange Network staging zone, where users come together to build new Q&A sites
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.
User Experience
Q&A for user experience researchers and experts
Theoretical Computer Science
Q&A for theoretical computer scientists and researchers in related fields
Mathematics
Q&A for people studying math at any level and professionals in related fields
Physics
Q&A for active researchers, academics and students of physics
English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
Stack Apps
Q&A for apps, scripts, and development with the Stack Exchange API
TeX - LaTeX
Q&A for users of TeX, LaTeX, ConTeXt, and related typesetting systems
Programmers
Q&A for professional programmers interested in conceptual questions about software development
Science Fiction & Fantasy
Q&A for science fiction and fantasy enthusiasts
Photography
Q&A for professional, enthusiast and amateur photographers
Writers
Q&A for authors, editors, reviewers, professional writers, and aspiring writers
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