We have a new requirement to allow staff members to create blogs within our intranet and have other staff members be able to rate/comment and follow blogs.
For this I was going to create an asset builder to create a news item, with another for the comments/ratings, but seem totally stumped for the follow/un-follow mechanism.
What you would do is create a User Group that will hold all of the users that are going to be "following" the blog. Then, use a Bulk Mail Subscribe Page which will allow you to subscribe a user, or unsubscribe them (I would actually create one for subscribe, and another for unsubscribe). This will create a Bulkmail user.
Then, setup a Trigger with the Asset Created Action to send an email to that user group when a new blog News Item is created. That way, they will all get alerted when the blog is updated.