Blockbutler - Real-time transaction notifications for the blockchain
Coin Demo - Visual demonstration of how bitcoin transactions work
Notif.me SDK - A Node.js lib to send all your transactional notifications
BlockchainI.CO - Research, ratings and analysis on upcoming ICO’s
Pusher - Pusher is a hosted API for quickly, easily and securely adding scalable realtime functionality via WebSockets to web and mobile apps.
Blockchain Startups Map - Map & searchable database of 430 companies in 64 categories.