Promotions Manager is an eBay Store tool that lets you create promotions in several categories, including order size discounts; free shipping offers; sales events; related item discounts; and targeted coupons. Download your free copy of the tutorial — which includes information on how to track the results of your promotions — here:
http://pics.ebaystatic.com/aw/pics/sellerTools/pdf/PromotionsManagerSellerTutorial.pdf