Also: http://www.syncano.com http://www.syncano.com (freemium) http://www.pubnub.com http://www.pubnub.com (freemium) http://www.socket.io http://www.socket.

Also: http://www.syncano.com http://www.syncano.com (freemium) http://www.pubnub.com http://www.pubnub.com (freemium) http://www.socket.io http://www.socket.io (open source)