Dabbling in many different technologies, from Drupal/php/MySQL, to mobile dev with MonoTouch.
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
Programmers
Q&A for professional programmers interested in conceptual questions about software development
Programming Puzzles & Code Golf
Q&A for programming puzzle enthusiasts and code golfers
Database Administrators
Q&A for database professionals who wish to improve their database skills and learn from others in the community
Drupal Answers
Q&A for Drupal developers and administrators
English Language & Usage
Q&A for linguists, etymologists, and serious English language enthusiasts
Physics
Q&A for active researchers, academics and students of physics
User Experience
Q&A for user experience researchers and experts
Science Fiction & Fantasy
Q&A for science fiction and fantasy enthusiasts
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems.
Mi Yodeya
Q&A for those who base their lives on Jewish law and tradition and anyone interested in learning more
Meta Stack Overflow
Q&A for meta-discussion of the Stack Exchange family of Q&A websites
Bicycles
Q&A for people who build and repair bicycles, people who train cycling, or commute on bicycles
Ask Different
Q&A for power users of Apple hardware and software
Photography
Q&A for professional, enthusiast and amateur photographers
Server Fault
Q&A for professional system and network administrators
Theoretical Computer Science
Q&A for theoretical computer scientists and researchers in related fields
Android Enthusiasts
Q&A for enthusiasts and power users of the Android operating system
Geographic Information Systems
Q&A for cartographers, geographers and GIS professionals
Cross Validated
Q&A for statisticians, data analysts, data miners and data visualization experts
Computational Science
Q&A for scientists using computers to solve scientific problems
Motor Vehicle Maintenance & Repair
Q&A for mechanics and DIY enthusiast owners of cars, trucks, and motorcycles
Quantitative Finance
Q&A for finance professionals and academics
Ask Patents
Q&A for people interested in improving and participating in the patent system
Computer Science
Q&A for students, researchers and practitioners of computer science
LEGO® Answers
Q&A for LEGO® and building block enthusiasts
Musical Practice & Performance
Q&A for musicians, students, and enthusiasts
German Language & Usage
Q&A for speakers of German wanting to discuss the finer points of the language and translation
Christianity
Q&A for committed Christians, experts in Christianity and those interested in learning more
Physical Fitness
Q&A for physical fitness professionals, athletes, trainers, and those providing health-related needs
