I’ve seen a few people in the wild using Hypothes.is as a blog commenting system.[1][2] Since they don’t yet have separate support for Webmention or require a bit of programming to get notifications, I thought I’d highlight this particular implementation as it has a simple, but relatively elegant user interface for creating feeds to provide notifications for just such a use case.
One could easily wire up the output from this through a service like IFTTT, Zapier, Integromat, etc. to push the notifications to email, or other modalities as desired. 
It doesn’t give anything over and above what a Hypothes.is addict with some programming skills could already produce, but for those who are code averse, or just too busy with building other pieces of the Domain of One’s Own this could allow some simpler outputs.
If you are a tinkerer, there is a GitHub repo for the project.
While you’re at it, why not throw in the usernames of some of your favorite annotators and subscribe away in your favorite feed reader? Some of the best things I discover online are through colleagues’ annotations, I think, in part, because it’s a much higher level of engagement with the material than the pablum found in many Twitter feeds.
It could also be a good means of following annotations on some of your favorite hashtags in the system as well. Want to learn some new words? Follow wordnik in your feed reader. Want to know the state of the art in Open Education Resources? There’s a tag serious people are annotating with that you could follow in your reader.

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