There's been a lot of interesting long threads lately and I feel it's difficult to keep track of new comments after a few hours/days.<p>I've written a GreaseMonkey script that allows to instantly view new comments since your last visit. Hope it helps.<p>More info and source: http://github.com/adn37/HNCommentsHighlight
I built this functionality into a Safari and Chrome extension, that also pairs nicely with the alternative interface I built:
<a href="http://hckrnews.com/about.html" rel="nofollow">http://hckrnews.com/about.html</a>
Hi. Talking about this topic, there is SmartPeople (<a href="http://nasr.ath.cx" rel="nofollow">http://nasr.ath.cx</a>) which lets you subscribe to HN users and threads. You'll then receive any new comment made by any user, by e-mail. The same for the new comments made on a particular thread.
An impromptu code jam on the subject from 3 years ago:<p><a href="http://news.ycombinator.com/item?id=65307" rel="nofollow">http://news.ycombinator.com/item?id=65307</a>