The National Audubon Society is having a Birding the Net contest through November 7. Some cool prizes. You have to sign up through Facebook. Go to their page and "like" it to start the contest. Obviously this is a social media promotion. It also seems you have a better shot if you are on Twitter. I am not sure. I am going to play with it a little and will let you know how it goes.
So far, I have 2 of the 34 cards.