Also recommended is https://news.ycombinator.com/front, which shows you the frontpage stories from any day—a little bit like archive.org would do, except that it's not a snapshot, but a composite of all the front pages from a 24 hour period.
https://news.ycombinator.com/highlights is another good resource (and if anyone notices a great HN comment, past or present, they're welcome to nominate it for the highlights list! just email hn@ycombinator.com).
Thanks Dan, that is in fact exactly what my bookmarklet does, it generates a random date (2012-01-02) and appends it to `https://news.ycombinator.com/front?day=`. I think there should be a `random` link on the HN header links that does what I am currently doing, it would be useful to have it built-in.
Yep it's fairly easy to make a bookmarklet for /front but for /highlights it seems to depend on the id of the comment as a cursor rather than the date, so it would be nice to have them both as links in the header bar.