How can we keep content current?

System

We are looking to implement an automated system where TeamSite can send out email notififications to the designated content contributor after a certain period of time, based on when the file was last modified. Our purpose is to maintain currency of the content. Would this be possible? If so, how? I was thinking that the Metatagger can be involved to designate the contributor. I also thought that maybe the "Last Modified" field can be extracted and be used as a trigger.

Here's a scenario we would like to see: TeamSite periodically scans the whole workarea, maybe at the end of each day, to see which files have not been modified for, say, 6 months or a year (it can be arbitrarily chosen - maybe it's something we can attach to the document via MetaTagger as well) by comparing the "Last Modified" date with the system date, which should be today's date. TeamSite would then send out an email to the doc contributor, extracted from the metatag attached to it. The owner would have to reply, say within a day or so, choosing to say that the file does not need to be updated, or update as necessary, then kick off a review workflow after that. If no response is received, the branch admin gets notified to take proper action.

We already have a review workflow in place that does send out email notifications, but they are triggered only from the workflow.

I'd really appreciate it if anyone has any ideas on how this can be implemented. Thank you.