I left this blank for a long time. Then I realized I could earn a badge for typing a few keys. How many keys do I need to type?
The Workplace
Q&A for members of the workforce navigating the professional setting
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems.
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
Mathematics
Q&A for people studying math at any level and professionals in related fields
Academia
Q&A for academics and those enrolled in higher education
Web Applications
Q&A for power users of web applications
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
Science Fiction & Fantasy
Q&A for science fiction and fantasy enthusiasts
TeX - LaTeX
Q&A for users of TeX, LaTeX, ConTeXt, and related typesetting systems
Bicycles
Q&A for people who build and repair bicycles, people who train cycling, or commute on bicycles
Physics
Q&A for active researchers, academics and students of physics
Database Administrators
Q&A for database professionals who wish to improve their database skills and learn from others in the community
Server Fault
Q&A for professional system and network administrators
Cross Validated
Q&A for statisticians, data analysts, data miners and data visualization experts
Personal Finance & Money
Q&A for people who want to be financially literate
Computer Science
Q&A for students, researchers and practitioners of computer science
Writers
Q&A for authors, editors, reviewers, professional writers, and aspiring writers
Area 51
Stack Exchange Network staging zone, where users come together to build new Q&A sites