The Daily Grind: What little events do you celebrate?

It's Saint Patrick's Day, and if you're in the US that means a celebration of Irish culture... or at least, it means a celebration of wearing green clothing and drinking an exceptional amount for the middle of the week. And while it's not the biggest holiday, some people look forward to it as much or more than major seasonal events. A few games even celebrate the event, such as Fallen Earth with a pub crawl and Everquest II with its Brewday celebrations. It's a holiday with no real overarching purpose except enjoyment, and that's hardly a bad goal.

Every game has little events that keep running long after they're no longer hugely pertinent. Every gamer has anniversaries or dates they remember, or holidays that they feel are important even if the game doesn't have a holiday event. So what small holidays or events do you observe in your favorite games? Do you make a point of memorizing important in-game lore dates and celebrating their anniversaries? Do you take part in no-longer-vital elements, such as the Elemental Invasions in World of Warcraft? Or do you just take the opportunity on days like today to outfit your Star Trek Online crew in green uniforms and hang around drunk?