In this recent New York Times article comparing IBM and Apple, I found this item fascinating.
Companies typically try to manage payments so they collect cash from customers slightly before they have to pay suppliers, thus making money by investing the cash before payments are due. Apple collects its cash in 25 days, on average, and pays its suppliers in 85 days — an extraordinary, 60-day spread that generates an extra $1 billion in cash flow a year, estimates A. M. Sacconaghi Jr., an analyst at Bernstein Research.