Downvoted, only commented as a way to reference this later.

Has HN considered a bookmark or favorites feature like dBforums?

HN does have a "favorite" feature. Click on the timestamp of the comment and you should see a "favorite" link. There's a similar link for submissions. Favorites can be referenced via your profile page. Or are you thinking of something other than this?

If you go into your own profile, the bottom two lines show items you upvoted or favorited. Upvotes are private. Favorites are public.

Your browser has its own bookmark feature, use that.