The Changing the Present app allows users to give "meaningful gifts" that contribute $1 each to a progressive cause. The idea could resonate with Facebook's users for a number of reasons:

• Many of Facebook's users are young, and $1 is a small enough amount that it seems like an affordable way to give to charity. Changing the Present frames its offers in such a way that $1 also seems like it can go a long way.
• It incentivizes giving by allowing users to interact on a personal level with friends and effect positive social change with and for their friends. Giving gifts is fun (Facebook's $1 gifts remain popular even in the face of so much free competition), so it is smart to tap into that trend.
• It publicizes giving. It will be harder for people to receive a gift without returning the sentiment when it is tied to a worthy progressive cause, and the $1 price tag means nearly all of Facebook's users can afford an in kind response.

It is interesting to see how non-profits are utilizing web 2.0 sites and ideas to socialize giving and raise money. Changing the Present is tapping into Facebook in a smart way that could raise a lot of money for non-profit causes, especially with the holiday season fast approaching.

Update: Allen Stern points me to a video he made of Changing the Present presenting their Facebook app at the NY Tech Meetup last week over on CenterNetworks.