1. You can collapse comments in threads. If you're logged in, collapses persist across page refreshes and devices for a week.
2. You can tell which way you voted and undo a vote if you want. An 'unvote' or 'undown' link appears after a post's timestamp when you vote.
3. Save and share the best stories and comments. Click on a post's timestamp to go to its page, then click 'favorite' at the top. Your favorites are linked from your profile, and you can browse other users' from theirs.
4. On the front page and /newest, click 'hide' if you no longer want to see a story. The next story in the list will slide up at the bottom. If you change your mind, visit /hidden and click 'unhide'. If you're logged in, hidden stories persist for a week.
5. Find out which stories were the most popular on HN on a given day by visiting /front?day=yyyy-mm-dd. You'll see all the front page stories for that day, sorted by how much time they spent there. For example, Alan Kay's AMA had the most front page time on June 20: https://news.ycombinator.com/front?day=2016-06-20.
Finally, I'm pleased to introduce sctb, a.k.a. Scott Bell, as a Hacker News moderator. Scott has been moderating HN incognito for a long time, but starting today he and I will be sharing the public part of the job. Since Scott is familiar with all aspects of HN moderation, you shouldn't notice any changes in practice; this is just an internal refactoring to enable such innovations as vacations and a day off. Scott is my cofounder from Skysheet (YC W09), an excellent programmer with a meticulous eye for detail, and a thoroughly decent human being. Please welcome him and be nice!