English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
History of Science and Mathematics
Q&A for people interested in the history and origins of science and mathematics
Meta Stack Exchange
Q&A for meta-discussion of the Stack Exchange family of Q&A websites
Русский язык
Cайт вопросов и ответов для лингвистов и энтузиастов русского языка
Worldbuilding
Q&A for writers/artists using science, geography and culture to construct imaginary worlds and settings
Politics
Q&A for people interested in governments, policies, and political processes
Cryptography
Q&A for software developers, mathematicians and others interested in cryptography
Russian Language
Q&A for students, teachers, and linguists wanting to discuss the finer points of the Russian language
Biology
Q&A for biology researchers, academics, and students
Cross Validated
Q&A for people interested in statistics, machine learning, data analysis, data mining, and data visualization
Linguistics
Q&A for professional linguists and others with an interest in linguistic research and theory
Mathematics
Q&A for people studying math at any level and professionals in related fields
Artificial Intelligence
Q&A for people interested in conceptual questions about life and challenges in a world where "cognitive" functions can be mimicked in purely digital environment
Space Exploration
Q&A for spacecraft operators, scientists, engineers, and enthusiasts
Aviation
Q&A for aircraft pilots, mechanics, and enthusiasts
Stack Overflow
Q&A for professional and enthusiast programmers