Is there a way to subscribe to changes to a folder (e.g. new documents posted or deleted) or a document (e.g. updates done)?

I am aware of the daily/weekly activity report, but this is for the entire project. I would like to get an immediate notification when activity occurs related to a specific folder or document.

It would be much like the functionality on this "Enter your idea" page; at the bottom of the page I can check the box and "receive a notification e-mail when a new comment is posted on this idea".

Thanks,
John