Stack Overflow
Q&A for professional and enthusiast programmers
Super User
Q&A for computer enthusiasts and power users
Ask Different
Q&A for power users of Apple hardware and software
Personal Finance & Money
Q&A for people who want to be financially literate
Electrical Engineering
Q&A for electronics and electrical engineering professionals, students, and enthusiasts
Video Production
Q&A for engineers, producers, editors and enthusiasts spanning the fields of video and media creation
Web Applications
Q&A for power users of web applications
Spanish Language
Q&A for linguists, teachers, students and Spanish language enthusiasts in general wanting to discuss the finer points of the language
Ask Ubuntu
Q&A for Ubuntu users and developers
Bicycles
Q&A for people who build and repair bicycles, people who train cycling, or commute on bicycles
Meta Stack Exchange
Q&A for meta-discussion of the Stack Exchange family of Q&A websites
Arqade
Q&A for passionate videogamers on all platforms
Server Fault
Q&A for system and network administrators
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems
Database Administrators
Q&A for database professionals who wish to improve their database skills and learn from others in the community
Academia
Q&A for academics and those enrolled in higher education
Music: Practice & Theory
Q&A for musicians, students, and enthusiasts