You can write for the RabbitMQ discussion lists if you are willing to contribute a plug-in for RabbitMQ (it may turn out that someone else is already writing or has already written about a similar plug-in). If you are eager to contribute to the RabbitMQ code base, you may start by first forking the particular RabbitMQ repository and writing good unit tests for the features that are not sufficiently covered by tests. After that, you can prepare a pull request for the particular RabbitMQ repository and incorporate a feedback on your changes. Another thing is improvements in the source code—although Erlang sources are quite concise, it isn't impossible to put some code here and there—if you do this then you can contribute by preparing a pull request with improvements; however, first you need to make sure that someone else is not working on the same issue by checking the issue list for the corresponding RabbitMQ project in GitHub.