Buy a couple of Holiday themed scratch lottery tickets, place a business card on each chair and put a number on the back of each business card. During dinner ask everyone to check their card, if they have the one with the number you call on it they could win up to (whatever the top prize is on the ticket you bought). Ask the winner to come forward. Have them scratch off the card while you wait, and emcee it. If they.... win GREAT! If not tell everyone to hold on to their card because there is going to be another drawing later. If you have another drawing that's fine, if you don't then your card is in their pocket.
Try this for any party or occasion.