Promotions Manager

Special Promotions Magento extension by Amasty (http://amasty.com/special-promotions.html ) will help you attract customers with exclusive promotions like 'buy X product get Y product with 30% discount', 'Each 2nd shirt for 50%', 'Get 10% off if placed more than 3 orders before', 'Buy 3 products and get 50% off for the cheapest' and many more.