http://sweeneymath.blogspot.com/2012/07/the-best-professional-experience-of-my.html
I've enjoyed reading the reflections on Twitter Math Camp (#tmc12) and I hope soon this kind of self-organized professional development opportunities are too numerous to count. Different attendees took away different things from the camp/conference, but I like Sean Sweeney's single sentence summary: "I've never been more excited to teach in my life."