A couple weeks ago my awesomely creative sister invited everyone over to her house for a Christmas party. She challenged everyone to do service for others and to keep track of how much they did. At the party she handed out "Service Bucks". One for every act of service you rendered.
We then used our "Service Bucks" to bid on presents that were being auctioned off.
Service Bucks (aka index cards)
"Who'll start the bidding? One dolla'! One dolla', do I hear two? Two dolla', who'll give me three?
Three! Going once, going twice. Sold!!!!