The annual European Hitchhikers' Meeting.

If you ever hitchhiked or you're dreaming of getting into thumbing BIG TIME be there! Lovely people, lovely nature, lovely program - made by hitchhikers for the hitchhikers. And it's free!

Exact location:
http://hitchwiki.org/community/hitchgathering/location/

More info:

http://www.hitchgathering.org
http://hitchwiki.org/en/Hitchgathering/2012
https://www.facebook.com/events/389721054421301/

(Please note that the event goes on as long as there are people there. The three-day limit is a stupid CS bug!)