What raffle or giveaway -- if any -- has produced the most return on attracting new customers (or keeping old ones)?

I'm referring to items that aren't discounts and don't pertain to the storage industry. For example, this San Diego facility is raffling off iPod shuffles.

If you don't have a success story, maybe you have a story about a failed giveaway that was a waste of money. Let others learn from your mistakes!