This is an amazing idea that uses many of the rules of conventional direct mail on Facebook. More importantly, it works!
Here's the backstory: IKEA opened a new store in a small town in Sweden called Malm. They didn't have much of a budget to announce their grand opening, so they decided to spread the word by setting up a Facebook page. Then they loaded a bunch of photos of their showrooms onto the page and put out a message to all their fans - whoever was the first to 'tag' an item in one of the photos would win the item. (If you're not familiar with Facebook, tagging is intended to be used to identify people in photos but this is a fantastic new application of existing functionality.)
As you can image, news spread like wildfire, the store got thousands of new FB fans, and IKEA got its merchandise in front of thousands of eyeballs. It also got a lot of publicity for the creative marketing campaign.
This idea has endless possibilties, and Facebook is free. Think about how you can put the viral power of Facebook to work for your business. Do you have a business fan page? How can you use it to get prospects to take the first step? How could you design a direct mail type offer with a bonus and disseminate it on Facebook? It's worth thinking about.