A modules that would allow Following/Subscribing to a particular Tag

Hi,

I'm looking for a module that would allow users to "Follow" particular Tags, in a way that would work with Views. I'm not sure if I can "Flag" taxonomies and later generate views like that. And Subscriptions module sends e-mails, rather than do anything with the view. Think of it as a module that Flags tags rather than just Nodes. The river of news that I'm trying to build is like Twitter, but instead of following only people, the user can also follow Taxonomy Tags or Categories (with a choice of content types).

Here's what I mean:
* Mary Smith clicks on a particular Tag (or Category or any other taxonomy that administrator has assigned as "Followable").
* This brings the usual drupal's list of all nodes under that taxonomy.
* But next to it Mary Smith sees a block which says "Follow taxonomyFoo in your mini-feeds"
**** and below that the she is given check-box options of all content types assigned to that particular taxonomy vocabulary ([]New Events , []new Groups, []new Blog posts, and even [] new People ... if we're using Usernode or something like that)
* Later on Mary Smith goes to her Mini-feeds (river of news) and among other items she also sees the content types from the tags that she is following (this river-of-news would be constructed with Views)

But I don't know if there is a module that would allow to "Follow" tags, which can be used to construct Views.

Any suggestions?