BookMooch - BookMooch is a community for exchanging used books.
Cool Cousin - Shaking up the travel world with good old human connection
SLOWLY - Make pen pals from your smartphone
Party with a Local - Party with a Local is a free app that connects travelers with locals that want to party.
InterPals - InterPals is a friendly community of over 5 million friends, language learners, travelers and penpals.
Triip.me - The happiest way to travel in 227 countries