Open Conference Organizing
There are a lot of great Open Source conferences out there, some of them organized by volunteers, some of them oranized by user groups, some by commecial entities, but none of them is so open as the last DrupalCon,
In all its awesomeness the DrupalCon DC organization actually
published it's internal financial details for everybody to view.
Try beating that :)
Oh and while we are talking about conferences .. Fosdem has a YouTube channel with a lot of recorded fosdem talks available.