Amazon is trying to enhance its seven merchandise-distribution centers. The company, based in Seattle, has been criticized for building such capital-intensive structures, but Jeff Wilke, the general manager for operations, said that Amazon's size required massive internal controls on inventory and orders. ''We could not deliver the same performance if we cobbled together some outsourced partners,'' he said. Amazon also intends to furnish same-day delivery for some top-selling products -- books, CD's and toys -- to customers through a partnership with Kozmo. (Last December, Amazon invested $60 million in Kozmo, which uses bicycle messengers in 10 cities to whisk movies, snacks and other easily carried items to urban dwellers.) CITY couriers like Kozmo and Urbanfetch store products close to their customers, much as Amazon or Webvan does, but on a reduced scale.