Multisite Individual Backup Plugin

Hello All,
I am wondering if you have had any luck using Backup Plugins in a Multisite environment?
I am looking for a plugin that will allow each individual blog to be backed up by it's owner complete with Database and Files. Is this even possible???

My reason for this is we are using WPMU to power an ePortfolio site for students. They need to be able to take a snapshot/export of what they have created with them when they graduate.

Are there any good solutions for exporting content and files/docs that may have been uploaded to a blog?