I love the discussions on Hacker News. I typically find the comments more interesting than the article itself, and I bet I'm not alone in that sentiment.
Unfortunately, the discussion half-lives are painfully short. Once an article moves from the frontpage, discussions quickly die off. New comments are also difficult to find in large, threaded discussions. This seems to be one of the more common complains with HN.
I wrote a greasemonkey script that identifies and highlights new comments. I've been using it for several days now and am pleased with how much better the HN experience has become.
It isn't anything fancy, just hoping to improve the user experience for similarly frustrated individuals :)
https://github.com/polyfractal/HNHalfLife