Stack Overflow
Q&A for professional and enthusiast programmers
Meta Stack Exchange
Q&A for meta-discussion of the Stack Exchange family of Q&A websites
Mathematics
Q&A for people studying math at any level and professionals in related fields
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems
Super User
Q&A for computer enthusiasts and power users
Area 51
Q&A for proposing new sites in the Stack Exchange network
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
Theoretical Computer Science
Q&A for theoretical computer scientists and researchers in related fields
Reverse Engineering
Q&A for researchers and developers who explore the principles of a system through analysis of its structure, function, and operation
Server Fault
Q&A for system and network administrators
Homebrewing
Q&A for dedicated home brewers and serious enthusiasts
Bitcoin
Q&A for Bitcoin users, developers, and enthusiasts
Web Applications
Q&A for power users of web applications
Information Security
Q&A for information security professionals
Emacs
Q&A for those using, extending or developing Emacs
Skeptics
Q&A for scientific skepticism
Stack Apps
Q&A for apps, scripts, and development with the Stack Exchange API