Users on my site struggle with "follow." They don't want to follow *everything* in an entire group, nor do they want to follow one atom of content (post, document, event, person, topic, etc).
Canonical example is "i want to follow new items in my group(s) of a specific content type" --- maybe just new events, or new documents, or new posts.
there are probably other equally good notions of mid-level channels of content that people want to follow. Let's improve ability to follow those mid-level channels of content