When our raffle has been drawn at the end of the interval, we ask everyone to keep hold of their tickets. Then, if there isn't time for a full run round the room to finish off the evening, we raffle the remaining spots. If your number comes out, you can either sing a song or nominate someone else to do so. This can be great fun and it gives non-performers a bit of power which they always seem to use to good effect.
PS I've won the mystery prize in the velvet bag at Cottingham... nice!
PPS We've been the paid performer at another club in which the raffle prize of a box of Quality Street was passed around during the first song of our second set.......... I am in full agreement with Vin about crisp packets!