Reddit certainly attempted this a few years ago. They had a 'recommended' tab in their main navigation. It worked about as well as their search at the time (ie. completely useless).
If I recall, it was based on your activity (this was pre-subreddits) so if you interacted with lots of political stories, for instance, similar political stories would be suggested.
The problem was if you downmodded a bunch of articles involving Ron Paul, your recommended links would be Ron Paul articles.
If I recall, it was based on your activity (this was pre-subreddits) so if you interacted with lots of political stories, for instance, similar political stories would be suggested.
The problem was if you downmodded a bunch of articles involving Ron Paul, your recommended links would be Ron Paul articles.