Stack Overflow
Q&A for professional and enthusiast programmers
Meta Stack Exchange
Q&A for meta-discussion of the Stack Exchange family of Q&A websites
Area 51
Q&A for proposing new sites in the Stack Exchange network
Mathematics
Q&A for people studying math at any level and professionals in related fields
Stack Apps
Q&A for apps, scripts, and development with the Stack Exchange API
Video Production
Q&A for engineers, producers, editors and enthusiasts spanning the fields of video and media creation
Worldbuilding
Q&A for writers/artists using science, geography and culture to construct imaginary worlds and settings
WordPress Development
Q&A for WordPress developers and administrators
Photography
Q&A for professional, enthusiast and amateur photographers
Super User
Q&A for computer enthusiasts and power users
User Experience
Q&A for user experience researchers and experts
Software Engineering
Q&A for professionals, academics, and students working within the systems development life cycle
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems
Ask Ubuntu
Q&A for Ubuntu users and developers
Server Fault
Q&A for system and network administrators
English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
German Language
Q&A for speakers of German wanting to discuss the finer points of the language and translation
Raspberry Pi
Q&A for users and developers of hardware and software for Raspberry Pi
Open Data
Q&A for developers and researchers interested in open data