BookMooch - BookMooch is a community for exchanging used books.
Glider - The automated deal desk. Glider streamlines the contract process, identifies bottlenecks, and brings visibility into the "last mile" of your sales funnel
BookCrossing.com - It's the World's Library. It's a smart social networking site.
B21 Invest - Crypto investments simplified
Random PenPals - Get a quarantine PenPal in 10 seconds
Coinvision - AI-powered data for the cryptocurrency and ICO market