Keep'em Busy.
There are different tactics, beyond fantastic content or service, you can resort to in order to retain visitors for longer and keep them storming back. From recommendation emails to forums to regular contests, anything is better than a cold goodbye while a deal is clinched. If you think about how difficult it was to attract a visitor in the first place, you should be able to appreciate the need to keeping them happy while on your site and reaching out after their exit.