Ability to backup a project
It would be useful to have a feature/plugin that would allow a Project Manager (or equivalent role) to backup all the files and information from a Redmine project. Maybe this could be implemented through a plugin, and would basically grab all the files and data and save them as a zip file as raw data. For bandwidth constraints, the number of times this could be done could be limited by admins.
Down the road, it'd be good to have a feature to upload a project to a new instance of Redmine, allowing for true data portability.