eBay is introducing a new sales analysis tool this September in the US, and the following month in the UK.

The new eBay Listing Analytics application will provide sellers with insight into how their fixed price and multi-quantity listings are performing. Listing Analytics will help sellers identify their best and worst performing listings, and revise them to maximise sales.

eBay's Sales Reports has some similar functions to Listing Analytics but competing third party applications are thin on the ground at the moment.

More information (UK version).