If you go to your personal node/homepage/whatever-you-call-it and click "write-ups", you get your ALL your posts -- starts or replies -- in reverse chronological order (newest first). So it's just a matter of clicking on the last few to see if anyone has replied to those.

Technically, possible. Will I do it? No way. Will I even remember which ones I've seen and which ones are new? Absolutely not.

If you are not logged in constantly, it's hard to understand how you could have so many urgent items here so as to require email notification.

Urgent? Nothing on Perlmonks has ever been urgent. And why email notification?

I would think a notification of replies to your replies (or replies to that, replies to that, etc) would be rather simple. Currently, if X replies to Y, Y gets a message in his/her inbox. Simple change it to not just notify Y, but to all (unique) posters up from X to the OP. (This is not to be implied I'm making any request whatsoever).