FrOSCon (Free and Open Source Software Conference) is an annual (since 2006) two day conference in Germany at the end of of August. It has free admission for everyone.
The conference revolves around a rich schedule of talks, highlighting current topics in Free Software and Open Source. Moreover, developers will be offered a large Free Software / Open Source space, allowing them to organize their own meetings or even their own lineup of events.
Additionally, exhibition space will be available to companies and projects, so they can present themselves to the visitors.
Speakers can normally get a sponsored room in a hotel in Siegburg.
Further, there are recommendable cheap hotel rooms available in Troisdorf or Porz, both locations are nearest to the airport of Cologne and can be reached easily by public transport (train or bus) from Cologne or Siegburg/Bonn (with ICE train station).
The social event takes place on Saturday evening at the event location right after doors are closing.
The conference is free of charge and you can just hop by. As soon as a booth is requested you can have the point of contact to FrOSCon add you into the system to get an exhibitor badge and access to on-location catering.