Ask HN: HN Email Subscription?

Could someone please make a service that would let people subscribe to Hacker News threads and comments, and receive email notification? I'm thinking the feature set of such a service is obvious and self-explanatory, but permit me to enumerate some of the basic features:

1) Subscribe to any discussion node, from parent article down to leaf comment

2) Receive notification of any new comments that are descendants of subscribed nodes

3) Optional auto subscription for your own comments

I'm sure many of us would agree that Hacker News discussions are generally of high quality. Comments are usually thought-provoking, arguments solidly supported. What I have noticed, though, is that discussion on HN only proceeds for about one or two days in most cases. Yet, I think threads would carry on longer (and wouldn't degrade too much) if participants got notification of new responses.

I feel quite discouraged to post anything on an HN thread that is older than 48 hours -- I suspect extremely few people would read it, so I'd rather not spend my time. If I knew that HN article discussions tended to last longer, I'd be more encouraged to participate. As it stands, I can't always keep up with the latest news, and sometimes read news items 3 to 5 days after they are posted, but by then it's too late to participate.

If anyone could come up with an HN subscription service, I, for one, would be very grateful. :)