StatCounter - StatCounter is a simple but powerful real-time web analytics service that helps you track, analyse and understand your visitors so you can make good decisions to become more successful online.

Socket.io - Realtime application framework (Node.JS server)

AFSAnalytics - AFSAnalytics.

SocketCluster - An open, scalable realtime engine for Node.js

Woopra - Track your customers' web and mobile activity, forms, emails, support tickets and more, all in one place with customer analytics. Analyze and take action.

SignalR - SignalR is a server-side software system designed for writing scalable Internet applications, notably web servers.