The problem isn't that I don't know how I would accomplish this - I have a very good idea of how I would do this, I just can't take on such a project right now; so I was wondering if something along these lines already exists out there...

My point was that the existing tools can be made to do what you want, it's just a matter of setting things up the right way. It's not really a matter of coding, rather just configuring what's there (and you're going to have to do that with any hypothetical über-cron anyhow).