Yeah - that's what we call the old navigation aid, usually at the top left. But I'm talking about maintaining interest.
Users are commitment-averse. Maybe because so much of the web has evolved to suit adolescent males.
They won't commit to give you an hour, or half an hour. Or even ten minutes. You can probably get another click or two out of your users, unless you've really put them off. So you have to leave a trail of breadcrumbs. Just one more cool thing ("OK," the user thinks. "I'll see this and then move on.") Then another cool thing, and another. They might only commit to that one click at a time, but if you do it right you just might be able to keep them for as long as you want.