In yet another shopper come-on this holiday season, a slew of retailers are participating in "Free Shipping Day" (Thursday, Dec. 18), offering procrastinating shoppers one last shot to do their holiday shopping online and get it delivered -- for free -- just in time for Christmas.

The full list is on freeshippingday.com We hope it will be as big as Cyber Monday, he says.

While Free Shipping Day may seem like one last act of generosity before the holidays are upon us, it's also a last-ditch effort by retailers to boost flagging sales. After a season filled with aggressive discounting, closeout sales and last chance promotions, consumers are suffering from invented holiday fatigue, says Joe Ridout, spokesman for Consumer Action, a consumer advocacy group. There are only so many shopping extravaganzas that one can take seriously.

In fact, retailers have been offering free shipping deals all holiday season long -- and many will continue to in the days and weeks ahead. Online shoe seller, Zappos.com, for example, is participating in Free Shipping Day, but actually offers free overnight shipping on its web site all year long. In general, if you re spending a decent amount of money [on an online order] usually $25 to $100 every day is free shipping day with most of these merchants, says Ridout.

Even though Free Shipping Day isn't the only deal in town, this publicity stunt is gaining plenty of attention. Here's what bargain hunters need to know.

Plenty of restrictions can apply

Before you whip out your credit card to buy that $20 sweater, make sure the retailer doesn't require you to spend $25 or more to nab that free shipping deal. Many retailers require you spend a minimum amount before delivering products for free.

Other retailers only offer free delivery on certain products. High-end cookware seller, Sur la Table, for example, offers free shipping on coffee makers, knife-block sets and even high-end appliance like the Cuisinart stainless steel food processor, but you'll have to pay if you want those snowflake cookie cutters.

Other free shipping deals abound

With or without Free Shipping Day, more last-minute shipping deals are bound to pop up as Christmas approaches, says Dan de Grandpre, CEO of bargain-tracking site Dealnews.com. For true holdouts, Dealnews has compiled a list of merchants that based on last year s offers should offer free shipping as late as Dec. 22 and 23, including Coach and Zales. Knowles' FreeShipping.org also lists free shipping coupons to more than 850 retailers that are valid beyond Dec. 18.

Item discounts may outweigh savings from free shipping

Read our story about the best coupon sites

On CouponCabin.com, we found a coupon for 15% off at clothing retailer Timberland. Two women s scarves on sale came to $60.27 (including a $7 shipping charge), for a total savings of $9.30. To take advantage of Timberland's free shipping promotion, you'll have to spend a minimum of $100 and you'll only save $7.

Check shipping deadlines

To make sure your package arrives on time, check retailers' shipping deadlines. (Most merchants sites have a link to shipping and delivery information on their home pages, usually in the customer service section). Dealnews.com also publishes a list of holiday shipping deadlines for Christmas Eve delivery. FreeShipping has a similar guide on deadlines for more than 250 retailers.