Substitute popularity (karma bubbling) for relevance (tags+search). I open HN home page 2-3 times per day (seldom I need to click on more). Of all the results, 3-4 are relevant to me but I still need to quickly read all the titles to find them. Build something smart that lists only what is relevant to me and you have a killer app.
We built one - or more like, we're building one. Not a HN clone, but a tool to let you create a HN clone.<p><a href="http://postatic.com" rel="nofollow">http://postatic.com</a><p>It's a work in progress, but there are handful of cool sites that have been created so far.<p>Examples<p><a href="http://tools.robingood.com" rel="nofollow">http://tools.robingood.com</a>
<a href="http://self.postatic.com" rel="nofollow">http://self.postatic.com</a>
<a href="http://www.slackchats.com" rel="nofollow">http://www.slackchats.com</a>
Make submissions tag-able so i can customize my front page (perhaps only allow predefined tags). There are a number of topic-categories i do not care about and they withhold interesting links.