The Referring Sites Report on Google Analytics is helpful to those trying to determine the effectiveness of the links they have posted on other pages, be they banner ads or the existence of non-paid referrals.
Basically the information presented shows you what sites visitors are using to get to yours, this will help determine if the links you've placed on other sites are actually providing a return on investment by driving traffic to your site. For example, if you've placed an advertisement on a certain page, you would hope that this page would be a star player on your referring sites report. If not, perhaps you should consider placing your ads elsewhere.
But not only can you see the traffic volumes from referring sites, you can also gain insights into visit quality using the standard Google Analytics metrics: Pages/Visit, Avg. Time on Site, % New Visits and Bounce Rate.
By clicking on each referrer you can see the referral path (actual page on that website) they came in on. By changing the dimension to landing page you can see what page of yours they landed on.