We listened to a great presentation on how to use Magento to support and eBay sales channel. Ebay is a huge community where people will search legitimately for all sorts products, not necessarily for auctions. Retailers can establish their own presence/storefront or list products directly.
Retailers should be there - given the size and volume of eBay - and it's actually straightforward to deliver. Simply, there's an extension from M2Epro. eBay owns Magento, so it's "endorsed" and obviously a strategic option for them.
It handles direct from the Magento Admin Panel:
Listing/selling format/duration/categories etc
Product mapping & description
Via a system of templates, which make its easy to manage lots of different products. We've implemented it for one client and its reasonably straightforward and works well.
It also works with Amazon.