Notification bars are one of those website features which have been around for so long that they’re now quite unobtrusive. You know the sort of thing I mean: a bar at the top or the bottom of your web pages which ‘sticks’ in that position, even when people scroll by. I’ve put one on our website to advertise our Twitter feed, if you want to see the sort of thing I mean.
I really would recommend that you look at implementing one of these on all or part of your website. You surely must have news, offers and the like which you want to let visitors know about. If you use a clever enough system (like SumoMe on WordPress), it’s easy to specify rules, such as when and where the notification bar appears, so you can meet any objective (and indeed, objection).