"Professionally" I do PHP, but in my spare time I tinker in C++/Java etc. Playing with Node a little lately.
Server Fault
Q&A for professional system and network administrators
Photography
Q&A for professional, enthusiast and amateur photographers
Programmers
Q&A for professional programmers interested in conceptual questions about software development
Mathematics
Q&A for people studying math at any level and professionals in related fields
Android Enthusiasts
Q&A for enthusiasts and power users of the Android operating system
Unix & Linux
Q&A for users of Linux, FreeBSD and other Un*x-like operating systems.
Bicycles
Q&A for people who build and repair bicycles, people who train cycling, or commute on bicycles
Stack Apps
Q&A for apps, scripts, and development with the Stack Exchange API
Game Development
Q&A for professional and independent game developers
Role-playing Games
Q&A for gamemasters and players of tabletop, paper-and-pencil role-playing games
The Workplace
Q&A for members of the workforce navigating the professional setting
Meta Stack Overflow
Q&A for meta-discussion of the Stack Exchange family of Q&A websites
