One-day shipping is going to be the tactic of choice in the holiday shopping game this year, and there's no retailer better equipped at its efficiencies than the world's biggest online retailer, Amazon. But as you're doing your comparison shopping for all those gifts you have to buy, remember this comes at a price: $119 a year for Prime membership.

So let's do the factoring. Sure, we'll get some great gifts at great prices and in double-quick time with Amazon Prime. What other Prime perks make it worth the cost of membership for the 100 million or so Primers worldwide? We found a few.

Free Same-Day Delivery

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Santa's had the whole "one-day shipping" thing tucked into one night since days of Christmas yore. But you're no Santa, so you might have to turn to your Amazon Claus, er, Amazon.com and Prime perks to get that gift, stat. Today's Amazon Prime is all about getting more stuff to members at an ever-faster pace (above Amazon's recent efforts to speed up free two-day delivery to free one-day delivery; I've recently started getting several Amazon-shipped items in one day, free; the order defaults to one-day at checkout).

Now this: Free same-day delivery doesn't apply everywhere, mind you, but more than 10,000 eligible cities and towns and counting is a fairly wide swath. If your ZIP code, , offers same-day service, when you order before noon and choose the same-day shipping option at checkout, Amazon says the package will be delivered by 9 p.m. that night (Sundays included, and don't be surprised to see the U.S. Postal Service delivering, though I'm seeing more and more Amazon-branded delivery vans). If you order past noon, an option is next-day delivery. Two caveats: The same-day order