Physics
Q&A for active researchers, academics and students of physics
Mathematics
Q&A for people studying math at any level and professionals in related fields
Area 51
Stack Exchange Network staging zone, where users come together to build new Q&A sites
Cross Validated
Q&A for statisticians, data analysts, data miners and data visualization experts
English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
Programmers
Q&A for professional programmers interested in conceptual questions about software development
Graphic Design
Q&A for professional graphic designers and non-designers trying to do their own graphic design
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems.
TeX - LaTeX
Q&A for users of TeX, LaTeX, ConTeXt, and related typesetting systems
Server Fault
Q&A for professional system and network administrators
Cryptography
Q&A for software developers, mathematicians and others interested in cryptography
Computational Science
Q&A for scientists using computers to solve scientific problems