Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems.
German Language & Usage
Q&A for speakers of German wanting to discuss the finer points of the language and translation
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
Area 51
Stack Exchange Network staging zone, where users come together to build new Q&A sites
Stack Overflow
Q&A for professional and enthusiast programmers
Ask Different
Q&A for power users of Apple hardware and software
Theoretical Computer Science
Q&A for theoretical computer scientists and researchers in related fields
TeX - LaTeX
Q&A for users of TeX, LaTeX, ConTeXt, and related typesetting systems
Linguistics
Q&A for professional linguists and others with an interest in linguistic research and theory
Board & Card Games
Q&A for people who like playing board games, designing board games or modifying the rules of existing board games
