English is not my native language, I've been learning it since the age of 5, then in school, and two years in the university. But school lessons are nothing compared to video games (in terms of learning a language)!
Thanks GTA San Andreas and Metal Gear Sold 3 for that, I've played them in English. Later, GTA IV and MGS 4 helped with that, too, these games contain a lot of dialogues and are very good for learning the language.
I always had the highest grades on English both in school and the university, and it was much easier for me than for the most of my classmates. Now I can easily communicate on English-speaking forums. However, sometimes I see some rare words and have to open the Google Translator.
My native language is Russian, I can also read Ukrainian (because it's pretty similar, as well as Belarusian) but not speak it fluently.
I also know Serbian a little (travelled to Montenegro several times), it's more different from Russian, because it's a South Slavic language (unlike Ukrainian, which is East Slavic), but I still could talk to the locals without switching to English.
Tried to learn German, but there was no real need for it so I didn't go deep into this. However, sometimes I still try translating the Rammstein songs.