Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems.
Bicycles
Q&A for people who build and repair bicycles, people who train cycling, or commute on bicycles
Server Fault
Q&A for professional system and network administrators
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
Programmers
Q&A for professional programmers interested in conceptual questions about software development
Physics
Q&A for active researchers, academics and students of physics
Role-playing Games
Q&A for gamemasters and players of tabletop, paper-and-pencil role-playing games
Meta Stack Overflow
Q&A for meta-discussion of the Stack Exchange family of Q&A websites
Personal Productivity
Q&A for people wanting to improve their personal productivity
Russian Language & Usage
Q&A for students, teachers, and linguists wanting to discuss the finer points of the Russian language
Sports
Q&A for participants in team and individual sport activities
Area 51
Stack Exchange Network staging zone, where users come together to build new Q&A sites
