Sorry I don't have any ideas for games, but at our large events we have raffles and silent auctions where people can bid on gift baskets, and then winners are announced periodically in between events. The local groups and individuals donate the baskets and auction items.

Another thing I've seen is called Ask-It Basket, where people can write questions to the District representatives and coordinators, and then questions are answered at various times throughout the day.

Good luck with your conference!

My experience is like Freetime's - we've never had any games but we have had raffles and silent auctions. All 'things' are donated here too. Love the Ask-It-Basket idea! Good luck with your efforts!