PM system between players. Communication between player and website is done mainly through popup-like notifications.
Right now you get redirected to a match page where you get all the necessary connect strings in plain text or you can click a button to get automatically connected.
STV connect info next to the server name sounds easy enough to implement. We'll do that.
For the sub system... We could (probably) send everyone currently added as the needed class a notification asking if they want to sub? However I'm not sure how annoying that would be, I guess we'd need to make it an option to turn that off then.
Post game stats sounds like a decent idea too.
Flags next to player names could be a bit tricky. Website uses steam login, and while we can get the country from players' steam profiles they are not necessarily always set correctly (or set at all). One alternative would be getting the flag based on your current IP, but I strongly dislike that idea. Another one would be to make it so you can set it on your profile page but then again I don't like forcing people to provide any information before they can start using the website, and if it's not mandatory a lot of people won't have their countries set. If you got any better solutions feel free to post them!