I <3 Ruby, Clojure, Unix, and code that actually runs.
Programmers
Q&A for professional programmers interested in conceptual questions about software development
Stack Overflow
Q&A for professional and enthusiast programmers
Area 51
Stack Exchange Network staging zone, where users come together to build new Q&A sites
Server Fault
Q&A for professional system and network administrators
Computer Science
Q&A for students, researchers and practitioners of computer science
English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
Stack Apps
Q&A for apps, scripts, and development with the Stack Exchange API
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems.
Meta Stack Overflow
Q&A for meta-discussion of the Stack Exchange family of Q&A websites
Cross Validated
Q&A for statisticians, data analysts, data miners and data visualization experts
Game Development
Q&A for professional and independent game developers
Database Administrators
Q&A for database professionals who wish to improve their database skills and learn from others in the community
User Experience
Q&A for user experience researchers and experts
Android Enthusiasts
Q&A for enthusiasts and power users of the Android operating system
Homebrewing
Q&A for dedicated home brewers and serious enthusiasts
The Workplace
Q&A for members of the workforce navigating the professional setting
Personal Productivity
Q&A for people wanting to improve their personal productivity