First off, let me clarify, I don't mean in the sense of PSN Trophies, or Steam or Xbox Achievements (although, if there are any of those you're particularly proud of, that fits).
Basically, this is for any gaming moments you are particularly proud of that you want to share with the world.
For example, I've just had one.
I've been playing the F2P (or pay like $15 for three months if you're serious about it, which I eventually did) browser based Might and Magic game that launched last fall. It's not a Facebook game (although it gives you options to post about stuff you did in the game, on Facebook, but you aren't rewarded for it), and it doesn't have real time combat either. It's more like the text based strategy games of the internet days of old, where you make a bunch of actions, attack other kingdoms, etc, only this game is illustrated with four tiers of an isometric map, so that you can actually see what you're doing.
Anyway, the game has multiple servers, and it's also split up into 'seasons,' where each season has a specific objective that all the alliances on the server are striving toward - and the one alliance that gets that, wins.
tl;dr?
Our alliance managed to win the season, hurrah! I've never been in the top alliance/guild for any sort of of persistent online game before, so it was pretty cool, and I ended up pretty high in the rankings. We also get a ton of bonuses going into Season 2 - you can see my 'win' screen below (Carrot is one of the gaming names I use):
So what are some of your folks biggest personal gaming achievements and moments?