I have a site with a lot of for-purchase content. I also have some sampler content for "free".
A LOT of people download this sample content, and I would like to now only allow access to the free content if the user is willing to "like us" on facebook.
How can I implement this? I'm a rails developer, but it may not matter what the app is.
How can I ask a user to like us, and then verify that they have?