Party with a Local - Party with a Local is a free app that connects travelers with locals that want to party.
Frysbe - Frysbe: Make global friends at random and the fling app comes up with features to send messages to strangers from every corner of the world to expand your social circle.
Palaround - Meet people you should be friends with.
PenPal World - Connect with people all over the world
Babble - A more personalized social network
Unbordered - Unbordered app comes up with features to help you in finding the perfect language practice and exchange partners so you can practice foreign languages right through your mobile phone.