Droid Sheep is an android app that sniffs out passwords to various social media like facebook within a network like an airport or mcdonalds.
Works by ARP Poisoning making your phone the gateway ip.
This will not work if they use SSL - so this wont last long.
http://droidsheep.de/
http://www.droidsheepapk.com/
You need a rooted phone and busybox installed to get this to work.