A few weeks ago, Amazon introduced a new shipping offer. For an annual $79 fee, they'd ship any Amazon order by UPS Blue (2 day) for free. For another $4 per order, they'd ship it UPS Red (next day). One annual fee per household. Before this, to get free shipping, you'd have to order $25 or more, and accept slower fulfillment and the US Postal Service's whims.
Probably not for everyone, but my last American Express bill had 17 Amazon items on it, and that was fairly typical for my household. So, I figure, I'd be paying maybe $0.30 per order for 2 day shipping, no minimum. Not sure how Amazon will make any money on me with this, but I signed up the day it was announced.
And it works. For a few items, it has taken a day extra to fulfill, and they don't count weekends, but everything has arrived the day they promised. And I don't have to deal with my local post office which is not among the USPS's most efficient.
I find that I'm ordering single paperbacks and DVD's more casually, instead of ordering $30 at a time. Probably will spend more, but they're sending about twice the number of packages, second day. If they don't have an extremely good deal with UPS, they're going to lose money on me.
Not that that's particularly my problem as a consumer. But as a stockholder, I do wonder....