I've installed this component on all the Joomla servers I manage. Finally, a simple and effective version control app that my users's can use. I only allow editing from the backend, so I can't speak of how it work on the frontend. From what I've seen this will be perfect for correcting those "oops" mistakes when a page is changed that shouldn't have been.

Does exactly what it says. Provides a simple and clean module that allows users to easily sign-up for a Google Group subscription.