I just wrote a post that linked to a lot of other SN posts. For the main headings, I mentioned the stacker who wrote the linked post (e.g., "blah blah blah by @elvismercury") but then in other links of lesser prominence, I didn't do that because it would have interfered with the flow.

In the first example, the user that I @-mention would obviously get a notification, which is good. But in the second example, she wouldn't. This is bad because it denies that user the opportunity to know that her post was mentioned. (In theory, someone who followed the link could comment on her original post, which would generate a notification; but she still wouldn't know the origin of the new activity.)

Idea: as part of posting / commenting, when someone links to another SN post / comment, the creator of the linked post / comment gets an optional (can be disabled in settings) notification. I think this might, in practice, be a high-leverage feature, since more than once something I've written has been linked, and I stumbled on it later by accident, whereas if I had been notified immediately I would have jumped into the conversation and contributed to it in the window of time when that contribution might have ignited something more.