I particularly enjoy possesion workings at such events, one that springs to mind was a joint possession of Baphomet in the main arena of The Ministry of Sound. The two operators took in previously made up sigils, then standing in the middle of the room surrounded by a couple of thousand ravers oozing spare energy from every orifice, one operator evoked Baphomet on the other, when the operator considered Baphomet was present he flashed the sigil before Baphomet and then slung it into the crowd. The possessed operator then projected Baphomet into the other operator and repeat the sigil operation.
This went on for forty minutes with both operators slinging Baphomet backwards and forwards, finally collapsing onto the floor in exhausted laughter, we stood up to see a large space had opened up all around us, with ravers just gawping on and the DJ having spot-lighted us. We laughed and left the main hall.
Afterwards, several very stoned ravers approached us and confirmed that they had seen a huge grinning demon running backwards and forwards between the two of us. . .
(via the ever classic Chaos Matrix)