In real life I'm a programmer, mostly C/C++.
This kind of activity has resulted in an ability to quickly detect typographical, syntax, grammar (and sometimes even style) errors in written text. Sometimes a blessing, sometimes a nightmare. It was only matter of time to start polishing Wikipedia content as I browse it—at least the English part—quite often :)
English, however, is not the language that I'm most fluent in, so I'll try to be careful there.