I put together a simple collapsible comment browser for HN earlier today, as I'd found long HN comment threads to be somewhat difficult to parse ("Wait, what is this guy replying to?")

It's written 100 lines of javascript + jQuery, and the more enterprising could probably turn the code a bookmarklet as it can run entirely on the client side. Also works fairly well on iOS.

Hat Tip: Built on the Hacker News API: http://api.ihackernews.com/. Great stuff, although if you click a link and nothing appears, it's probably because the API returned a server error.

http://hncomments.com/