Stack Overflow
Q&A for professional and enthusiast programmers
Biology
Q&A for biology researchers, academics, and students
Worldbuilding
Q&A for writers/artists using science, geography and culture to construct imaginary worlds and settings
Science Fiction & Fantasy
Q&A for science fiction and fantasy enthusiasts
Parenting
Q&A for parents, grandparents, nannies and others with a parenting role
Mathematics
Q&A for people studying math at any level and professionals in related fields
Russian Language
Q&A for students, teachers, and linguists wanting to discuss the finer points of the Russian language
3D Printing
Q&A for 3D printing enthusiasts
English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
Writing
Q&A for the craft of professional writing, including fiction, non-fiction, technical, scholarly, and commercial writing
Chemistry
Q&A for scientists, academics, teachers, and students in the field of chemistry
Mathematics Educators
Q&A for those involved in the field of teaching mathematics
History
Q&A for historians and history buffs
Physics
Q&A for active researchers, academics and students of physics
Server Fault
Q&A for system and network administrators
User Experience
Q&A for user experience researchers and experts
Cross Validated
Q&A for people interested in statistics, machine learning, data analysis, data mining, and data visualization
Law
Q&A for legal professionals, students, and others with experience or interest in law
Software Engineering
Q&A for professionals, academics, and students working within the systems development life cycle
Psychology & Neuroscience
Q&A for practitioners, researchers, and students in cognitive science, psychology, neuroscience, and psychiatry
Computer Science
Q&A for students, researchers and practitioners of computer science
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems
Blender
Q&A for people who use Blender to create 3D graphics, animations, or games
Puzzling
Q&A for those who create, solve, and study puzzles