I am a mathematician by profession and quite a long-time (since around 1995 – as of now [2014], this means more than half of my life) TeX user by hobby.
I started with plain TeX, and much later (in the early 2000s) moved to LaTeX; I still use plain TeX occasionally (and when writing LaTeX classes/packages). Quite recently I also started to use ConTeXt.
I am a heavy Emacs user, though still a newbie – I started in 2001.
I have a blog about (among others) TeX and friends, located at http://mbork.pl/Content_AND_Presentation.
TeX - LaTeX
Q&A for users of TeX, LaTeX, ConTeXt, and related typesetting systems
Emacs
Q&A for those using, extending or developing Emacs
Mathematics Educators
Q&A for those involved in the field of teaching mathematics
Mathematica
Q&A for users of Wolfram Mathematica
Stack Overflow
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Personal Finance & Money
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Science Fiction & Fantasy
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Mathematics
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Board & Card Games
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Super User
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Academia
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MathOverflow
Q&A for professional mathematicians
English Language & Usage
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Christianity
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Role-playing Games
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Database Administrators
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Code Review
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Area 51
Q&A for proposing new sites in the Stack Exchange network