I feel like PC may have been one of the greatest contributors to improving my English. I reckon this is something a lot of people pick up when they frequent forum, whether English is their first language or not. But since PC is the only forum that I've ever really gone to, I feel like it's had such a bigger impact than anything else. A lot of the English I'm taught in school is already something I've learned simply through reading posts on here and picking up on certain patterns and such. In general my time on the internet has been a great contribution to my English, but it's not everywhere on the internet where you see a consistent use of correct English, so yeah haha.
I also feel like PC has been a great way to reflect on myself as a person, and change into someone, that I myself would like better. I'm not certain how many people do this, but sometimes I like to go back and read some of my older posts, usually recent enough so that some elements to my way of communicating and acting will still apply to me now, but still old enough so that it doesn't portray me exactly the way I am now. And I just look for patterns that I dislike and actively seek to avoid doing that in the future. I can't tell how many times I've stumbled upon an old post of mine and hated the way it's been structured. Like, feeling that my posts lack emotion, that I might have typically worded stuff in a way to which it would come off as rude, etc. And while it mainly applies to the way I communicate online, some of it is also applicable to real life.
From lurking in the D&D forum, I also learn a lot about issues that I may not have heard of otherwise. And in general I find it interesting to see the reactions of familiar faces to certain issues, so it often makes it more entertaining than simply reading an article about it.
I also learned that Lugia, despite being the guardian of the sea, is not a Water type. Long live logic!