swap-bot - Swap-bot is a online service that organizes group swaps and a community of creative individuals.

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.

BookMooch - BookMooch is a community for exchanging used books.

PenPal World - Connect with people all over the world

InterPals - InterPals is a friendly community of over 5 million friends, language learners, travelers and penpals.

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.