Kind of off topic, but I've been thinking about building a site like HN/reddit, but instead of ranking stuff based on how many votes it has, use machine learning to predict how likely a specific individual is to upvote it.<p>That way everyone's front page is based off what they tend to like, and what people who like similar stuff to them liked. That way you don't have to fracture stuff into 50 different communities and try to figure out what kind of content is acceptable in each, and what ones you want to subscribe to.