As far as making it longer, I usually click over to the second page of new submissions before I give up. I have no idea if that's typical, though. Perhaps you could keep track of how many pages people usually look at?
To use a person anecdote, when I come to HN I immediately look to the top. I have come to expect good stories up on top, and I'm sure I'm not alone in that sentiment.
This being a likely user behavior, you could game that behavior by putting 5 or so of the newest stories in a thinly bordered box, above the normal top stories. That way when people go looking for the top stories, they see the new stories, and are more likely to read and comment on the interesting ones.
This will preserve the normal UI of the site, with minor UX changes, while giving exposure to each story as it comes in. If I were to guess, most of the good stories that come in and languish do so because of a lack of exposure. I'm willing to bet that most people don't look at the newest page very often, expecting others to upvote the good stories onto the frontpage for them.
Whenever there's some important piece of news like the japan earthquake we have highly redundant discussions on many different articles. This is wasteful.
That way good content with poor headlines still has a shot.
- Give more karma to votes on new stories to compensate the extra effort to leave the front page.
- Display one or two random new items on the front page to increase exposure.
- UI change on front page. When mouse moves over the random new item box, display a popup overlaying page containing the new items to allow for upvotes. When mouse moves away, hide the new item page. It's more complicate to implement and might not work too well on phones but should remove the mental barrier to go to the new page.