Stack Overflow
Q&A for professional and enthusiast programmers
Science Fiction & Fantasy
Q&A for science fiction and fantasy enthusiasts
Electrical Engineering
Q&A for electronics and electrical engineering professionals, students, and enthusiasts
Computational Science
Q&A for scientists using computers to solve scientific problems
Worldbuilding
Q&A for writers/artists using science, geography and culture to construct imaginary worlds and settings
Poker
Q&A for serious players and enthusiasts of poker
Mathematics
Q&A for people studying math at any level and professionals in related fields
Super User
Q&A for computer enthusiasts and power users
Raspberry Pi
Q&A for users and developers of hardware and software for Raspberry Pi
Physics
Q&A for active researchers, academics and students of physics
Ask Different
Q&A for power users of Apple hardware and software
Skeptics
Q&A for scientific skepticism
Server Fault
Q&A for system and network administrators
Information Security
Q&A for information security professionals
Bitcoin
Q&A for Bitcoin users, developers, and enthusiasts