That's a great idea. I don't even think it's on our list. I'll add it.
We have an experimental feature to highlight new comments if you or anyone wants to give it a try - email hn@ycombinator.com. But you'll still have to scroll through the pages to find the new ones.
Consider whether we might be better off without that feature, which also makes it super easy to keep aging threads alive, which is something HN has subtly discouraged thus far.
