I use hnnotify.com. I am far more socially oriented than most people here and that fulfills my need to respond in a somewhat timely fashion to other humans who are trying to talk to me.
I am noting that because I don't know what you need that isn't being met by hckrnews.com or hn itself. I know there are other solutions out there but, for my needs, it works fine to show up whenever the heck I feel like and read what catches my fancy, but checking for replies to my comments used to make me nuts and now that piece of it is solved. I would not be surprised if I find myself wanting something else in the future when my life is different from what it is currently, but I think the solution that makes sense depends a great deal on what you need and I don't see an explanation of that (edit: I mean I don't see where you have clearly stated what you really need here).
I will note there is also http://rrrewind.com/
Best of luck.