Stack Overflow
Q&A for professional and enthusiast programmers
English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
Software Quality Assurance & Testing
Q&A for software quality control experts, automation engineers, and software testers
Meta Stack Overflow
Q&A for meta-discussion of the Stack Exchange family of Q&A websites
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems.
Drupal Answers
Q&A for Drupal developers and administrators
Ask Different
Q&A for power users of Apple hardware and software
User Experience
Q&A for user experience researchers and experts
Game Development
Q&A for professional and independent game developers
Android Enthusiasts
Q&A for enthusiasts and power users of the Android operating system
Programmers
Q&A for professional programmers interested in conceptual questions about software development
WordPress Answers
Q&A for WordPress developers and administrators
Server Fault
Q&A for professional system and network administrators
Personal Productivity
Q&A for people wanting to improve their personal productivity
English Language Learners
Q&A for speakers of other languages learning English
Philosophy
Q&A for those interested in logical reasoning
Cryptography
Q&A for software developers, mathematicians and others interested in cryptography
The Workplace
Q&A for members of the workforce navigating the professional setting
Spanish Language & Usage
Q&A for students, teachers, and linguists wanting to discuss the finer points of the Spanish language
Computer Science
Q&A for students, researchers and practitioners of computer science
Area 51
Stack Exchange Network staging zone, where users come together to build new Q&A sites