Here are several links to some of the biggest and best scene-parties:
THE PARTY is hold in Denmark between Christmas and New Year’s Eve every year since 1991, most of the time in Aars.
Mekka & Symposiom, another party, hold in Fallingbostel/Germany during the Easter weekend since 1995.
The Assembly, the biggest (and best? don’t think so!) event, hold in August every year since 1992, mostly in Helsinki/Finnland.