The Great Outdoors
Q&A for people who love outdoor activities, excursions, and outdoorsmanship
Answers OnStartups
Q&A for entrepreneurs looking to start or run a new business
Area 51
Stack Exchange Network staging zone, where users come together to build new Q&A sites
Programmers
Q&A for professional programmers interested in conceptual questions about software development
Physical Fitness
Q&A for physical fitness professionals, athletes, trainers, and those providing health-related needs
Personal Finance & Money
Q&A for people who want to be financially literate
Cross Validated
Q&A for statisticians, data analysts, data miners and data visualization experts
English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
Mathematics
Q&A for people studying math at any level and professionals in related fields
Server Fault
Q&A for professional system and network administrators
Bicycles
Q&A for people who build and repair bicycles, people who train cycling, or commute on bicycles
Game Development
Q&A for professional and independent game developers
Geographic Information Systems
Q&A for cartographers, geographers and GIS professionals
Physics
Q&A for active researchers, academics and students of physics
Web Applications
Q&A for power users of web applications
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
User Experience
Q&A for user experience researchers and experts
WordPress Answers
Q&A for WordPress developers and administrators
The Workplace
Q&A for members of the workforce navigating the professional setting
Sports
Q&A for participants in team and individual sport activities
Ask Patents
Q&A for people interested in improving and participating in the patent system
Programming Puzzles & Code Golf
Q&A for programming puzzle enthusiasts and code golfers