Are you using a message queue? Perhaps you are using something like AMQP to keep your various applications together? What sort of uses are you putting your message queue to?
I use MQ's to queue things that I want to do that are computationally expensive but shouldn't impact the user experience. A feature that is necessary but doesn't require immediate execution.
For example, I use a MQ to manage the creation of thumbnails on a website that I manage when somebody uploads a new photo.
Ok...I will go first ;)<p>One of our clients is using a MQ to link a fleet of 550 electric vehicles to a head office app that checks for vehicle service issues.