Web purchases usually take at least a day to arrive, but that might not be the standard for long as e-retailers explore ways to get products to customers within hours of order time.

The latest example came Monday, when Amazon.com unveiled an alliance with Kozmo.com, a quick delivery service that will bring a selection of Amazon's books, music and toys to shoppers in less than 60 minutes.

"There are just some people who want instant gratification when they make a purchase, and they are looking for that same gratification when they buy on the Internet," said Stephanie Shern, global director in the retail consulting practice at Ernst & Young.

Web merchants have long touted the ease and convenience of shopping online. With an Internet hookup, consumers can find just about everything they could want ever to buy and avoid the aggravation of crowded stores.

Yet buying online does have its drawbacks for those wanting something immediately. The fastest shipment that most merchants offer is overnight delivery, and that usually comes with a hefty surcharge. Standard delivery takes at least three days.

"There are those people who want something in minutes, or else they think it is easier to just get it at a traditional store," said David Cooperstein, an analyst at the Forrester Research in Cambridge, Mass., an Internet consulting firm.

A handful of well-known e-retailers are now trying to figure out how speed up their delivery times — a not particularly easy task.

While these companies have the know-how to ship packages to customers nationwide from a centralized warehouse, there is a different set of logistics required to get goods to someone in a few hours time.

Quick delivery involves a local fulfillment system. Companies must have warehouses in the community being served and an army of people on hand to deliver each order.

With the costs of developing such systems running very high, many e-retailers have been keeping a close eye on the online door-to-door delivery services now in business in a few cities around the country.

Instead of creating their own system, the larger online retailers may be able to partner with the local services.

That's what Amazon.com is doing with Kozmo.com, a New York-based e-retailer that sells and rents videos and DVDs, as well as sells games, magazines, books and a small selection of food. All of its deliveries come within an hour.

Amazon.com announced Monday that it had invested $60 million in Kozmo.com and would eventually use Kozmo.com's infrastructure to help deliver a selection of its own books, toys and music within an hour.

Kozmo.com is available in six cities — New York, Boston, Washington, Seattle, San Francisco and Los Angeles. It delivers all its goods by messenger and does not charge a fee for delivery.

Kozmo.com won't be Amazon.com's only partner. Amazon.com spokesman Bill Curry said the Seattle-based online retailer will also explore opportunities to align itself with other one-hour delivery services.

Among those that could be on its list include Urbanfetch.com, another quick delivery merchant in New York that sells books, music, videos, electronics, games and health and beauty aids.

Also getting lots of attention are the online supermarkets, such as Homegrocer.com, Webvan.com and Streamline.com. Shoppers could buy a new video along with their peas and milk, and get them all delivered at once.