Qminder - Qminder works the way it sounds: It helps a company mind its queues.
Datadog - See metrics from all of your apps, tools & services in one place with Datadog's cloud monitoring as a service solution. Try it for free.
Zeplo.io - Message queue as service.
AppDynamics - Get real-time insight from your apps using Application Performance Management—how they’re being used, how they’re performing, where they need help.
slashQ - Queue management system
Zabbix - Track, record, alert and visualize performance and availability of IT resources