I find that you always stumble upon fantastic articles. Recently I learnt to accept that I will never be able to read all of them and that in-fact it's better if I don't. Instead I will read what interests me at the time (while it is on the front-page of HN) and if it disappears then so be it.

Though to answer the question, anything you upvote is saved in your user profile under 'saved stories'. That's a minimalistic way to track them. Instapaper is another great alternative.