M2E Pro is a Magento trusted (TM), award-winning extension, which allows merchants of all sizes to fully integrate Magento based system(s) into eBay/Amazon platforms.
This allows quick and simple creation as well as management of product listings (inc. automated synchronization of stock levels, pricing, and product details), import of eBay/Amazon orders, automated feedback posting for buyers and many other tasks which significantly reduce time required for listing maintenance.