Absolutely. These shopping sites are highly visited and your competition likely has their products listed on 3rd party sites. Many shoppers use these sites for comparison shopping and it is important that your products are visible. Your products need to be in front of as many people as possible, and this means presenting them in every economically viable channel. For most online stores, marketplaces like Google Shopping, eBay, and Buy.com are economically viable and tend to drive incremental revenue. Keep...