Specineff wrote:English. (Seriously.)
Me too.
Not that my english is perfect (far from it), but having to read english text, then going out at international gaming forums and try to write texts in english made my english get from "I can barely understand that" to "Pretty acceptable". I can even watch american movies without subtitles nowadays, and I had to actually speak with people who didn't know any other language but english, and I got it pretty well.
So, I thank gaming for that.
I also believe gaming helped be develop my logical thought, which helped me becoming a pretty decent computer programmer, and then a computer programming teacher. This was also helped by the fact I was first curious games were done, and then later I want to make my own games.