One thing I've been working on on the side is a little project that uses a message broker to send and receive "auditing" events. Just briefly, the idea is that any piece of software might want to emit audit messages to log certain events that have occurred so that those events are captured for future reporting purposes. This project (call it rhq-audit for now) can provide a message broker if you need one, along with a high-level API that can be used to both emit and process these audit messages. For example, maybe you want your sales application to record each attempted login by a remote client, or maybe you want to record each sales order that has been submitted. Using the rhq-audit API, audit messages can be fired off on the message bus for later consumption by an rhq-audit consumer whose job it will be to store the audit record in a persistence store that can be used by reporting tools when audit reports need to be generated.
RHQ-Audit doesn't provide any reporting tools, but does provide a compact API that allows you to emit and store audit messages. You can persist your audit messages to a simple log file (see LoggerConsumer) or to a relationship database (see DataSourceConsumer), or to any custom backend (you would just need to implement your own BasicMessageListener and have the AuditRecordProcessor use it as its listener).
I separated out the message broker stuff (along with a generic and extensible consumer/producer API) into rhq-msg. rhq-audit extends rhq-msg to handle audit events. But the idea is rhq-msg can be used to provide a message bus along with an API for any type of messaging app you want to build.
In addition to the API, an embedded broker that you can use to embed in your VM or run standalone, and an extensible test API, there is also a custom Wildfly module extension that can be used to easily deploy a message broker inside your application server via Maven. See my previous blog on how to install that Wildfly extension via a mvn plugin.
To build and run the tests for rhq-audit and rhq-msg, all you need to do is run "mvn install" from the top level root directory.