AJAX-based upvoting: I click on the up arrow for a comment, and the page totally refreshes, and I'm at the top of the page. Then I have to scroll back down and find where I left off. Annoying.
Link to the news.ycom page in the RSS feed, rather than the external link, or in addition to the external link: If I want to comment on the external site, or read what other people have made, I have to go to the main news.ycom page and find the comment thread. This wastes maybe 30 seconds of my time, which can be important when I'm still formulating what I want to say and don't need the distraction.
