Delta recently expanded the functionality of their Ticket Counter app to include checking in to your flight, checking the status of your flight and access your Skymiles account- all without leaving Facebook.
They also added the ability to share your travel info with a friend. For people that spend a great deal of time on Facebook and also have a nasty habit of forgetting small things like giving your flight info to the people that need it, this is an awesome feature.
All of these new offerings are in addition to the ability to book a flight, which Delta started offering to their Facebook fans back in August.
Over the past few months, it seems like brands are really stepping up on Facebook and using apps to give most of the important functionality of their corporate websites. It will be very interesting to see what the future holds for both Facebook and corporate websites.