This is a demo interface for sending push messages. It is the same service as created by tokudu.com, just running on a different server.
It can be used in conjunction with an Android app to demo sending push messages. It could also be used on the iPhone or other platforms, but I don't have a ready link for an app that implements it. For more details, read the complete post How to Implement Push Notifications for Android.
IMPORTANT: You will need to obtain the sample Android app from github as described in the link, but in order to work with this server you need to make a minor change before you compile it. You should change the file src/com/tokudu/demo/PushService.java so that the variable MQTT_HOST is "test.mosquitto.org". You will also need to change the client id to "mosquitto/" instead of "tokudu/".
See more details on this server at test.mosquitto.org
Server status: Online