Stack Overflow
Q&A for professional and enthusiast programmers
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems
Mathematics
Q&A for people studying math at any level and professionals in related fields
Server Fault
Q&A for system and network administrators
Software Recommendations
Q&A for people seeking specific software recommendations
Cross Validated
Q&A for people interested in statistics, machine learning, data analysis, data mining, and data visualization
Geographic Information Systems
Q&A for cartographers, geographers and GIS professionals
Data Science
Q&A for Data science professionals, Machine Learning specialists, and those interested in learning more about the field
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
Computational Science
Q&A for scientists using computers to solve scientific problems
Game Development
Q&A for professional and independent game developers
Quantum Computing
Q&A for engineers, scientists, programmers, and computing professionals interested in quantum computing
Software Engineering
Q&A for professionals, academics, and students working within the systems development life cycle
TeX - LaTeX
Q&A for users of TeX, LaTeX, ConTeXt, and related typesetting systems
Skeptics
Q&A for scientific skepticism
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