The mqtt protocol is often used for sensors to communicate readings.
I found a github project to relay mqtt subjects to zabbix: https://github.com/kylegordon/mqtt-zabbix.
I'm using that, but it really is more elegant to directly provide an item type 'mqtt' that simply subscribes to a message and collects all published values.
The same applies of course to ActiveMQ and zeromq, but a separated ticket should be used for that.