InterPals - InterPals is a friendly community of over 5 million friends, language learners, travelers and penpals.
BookMooch - BookMooch is a community for exchanging used books.
PenPal World - Connect with people all over the world
Random PenPals - Get a quarantine PenPal in 10 seconds
swap-bot - Swap-bot is a online service that organizes group swaps and a community of creative individuals.
Cool Cousin - Shaking up the travel world with good old human connection