I would like it if HN could be divided into separate sub-topics, or have each submission tagged with a few topical tags, like "web development", "javascript", "compilers", "linux", "graphics", etc. For bonus points, allow HN to be customized for each user so that they can subscribe to their favorite topics, which then populate the front-page and /best page.
I find that keeping up with news on HN is essential to me learning new things and becoming more skilled in my field. However, HN caters to a wide variety of interests, and it is time-consuming to have to sift through a bunch of posts on topics that I'm not really interested in.