Cycling for Libraries is an interesting addition to this list as it is equal parts professional development for librarians and advocacy for libraries:
Founded in 2011, the Cycling for libraries is an international cycling conference for librarians and library lovers. It aims to advocate libraries and increase awareness of the valuable services and resources that libraries offer to the community. (About Cycling for Libraries)
This combination cycling tour and unconference, allows the participants not only the opportunity to come together and talk about libraries but also to visit a number of communities and local libraries along the journey. In 2013, their focus was on Public Libraries and they produced a number of resources on their website about the contributions public libraries make to their local communities.