jrush
It is a Linux command line application. Once installed you'll be able to control a bunch of features using a command like jrush user delete insteadof doing this in a web interface. for one or two tasks, it can be a bit simpler, for bulk tasks, invaluable.
It really is time Joomla had a command line interface. We're in the age of cloud applications, scaling, distributed architecture, yada yada yada. There simply may not be time, resources or artchtectural scope to only allow the website to be controlled by the Web interface.
More importantly, as a developer myself, there have been way too many times when an employer has asked me to interrupt my beauty sleep by performing tasks during the night so that if the site breaks it can be fixed with minimal user impact.
I have been able to implement Continuous Integration and deployment into my Joomla sites properly, so now deployment is a button click or a couple of commands, and it's smooth every time... So now can you - if you are working in enterprise, things like this are a must, and if you are not in enterprise, the advantages to being able to have quick, reliable deploys (which this is a part of) are still massive.
If you have any requests for new commands that you would like added, please go to our support forum and tell us, we'll be glad to add it, or, since jrush is pretty extendable, feel free to write modules for it and send them to us to be added.
Thanks, Dave