Connected Weddings does your seating chart for you
New Facebook app uses your social graph to make sure friends sit together.
My favorite app concept from the Facebook F8 Developers' Conference was Connected Weddings. Based on the fact that planning a wedding is a social affair (duh), it lets you connect with two different groups: the people coming to your event, and other people who are getting married. With the former, you can share stories and photos. With the latter, you can talk about your plans and get advice. But that's not the cool thing.
What I really like is that Connected Weddings will create seating charts for your wedding reception, based on the Facebook connections between your invitees. You can overrule the placements, but this concept is just cool. As anyone who's planned their own wedding knows, figuring out who to seat where is a difficult topology problem, and it's great to see the "social graph" applied to this real-world exam test.
The app's not out yet, unfortunately.
Somewhat related: Those trying to get to the wedding can use the Carpool app.