I took huge strides forward as a Gamemaster running my L5R game. I didn't call it an Open Table, but that's what it was. Anyone and everyone was welcome every other week for over a year. I never knew if I'd be running 6 players or 18, on any given session. And I loved it. It pushed me, it made me tell better stories, and it reminds me what my capabilities are as a GM, 14 years later.
Players sacrificed themselves nobly for Honor and Clan. A Shugenja of the Void, miscast a spell and slaughtered his comrades as punishment by the Kami, and he hid it to save face. And the survivors never spoke of it or asked him about it, so he could. My wife led the Crab to mighty victory and ignominious defeat. Her band became legendary for it's barbarism and heroism. The pursuit of rare, delicious pickles was the focus of a whole session and drove a Samurai to leave his Clan and seek refuge as a simple monk. A great Hero died in mere moments from a cruel, careless shot from a bandit's bow.
I'm thankful to everyone who spent even a moment at my table, teaching me how to be a better Gamemaster. Inspiring me to entertain them and teaching me new ways to tell them a story. Every game I've run since, that I've planned and plotted, lives in this game's shadow.