Editor's Note: The deal we posted here has expired, but MainStreet is constantly updating its deals and special offers.

Extending a deal marking 9/9/09, Restaurant.com has offered for 99 hours as of that date, a 90% discount on its gift certificates.

Diners who can enter the code “NINETY” at checkout can take 90% off already money-saving gift certificates until Sunday, Sept. 13 at 3 a.m. That means a $25 gift certificate for $1 as opposed to its regular price of $10 and a $50 certificate for $2 as opposed to $20, for example.

"Since 09/09/09 only comes around once, we are marking the date, in these times, with a sale that reminds people that they can still go out to eat and enjoy a great meal with friends and family," said Cary Chessick, president and CEO of Restaurant.com. The company says it wanted to offer a deal unlike anything consumers have ever seen before, but they may never see it again.

While the deal only lasts for a couple more days, the certificates are valid for a year from their purchase date.

Participating establishments can be searched for based on location, cuisine and alphabetically at Restaurant.com, which provides information, directions and photos of the restaurants.

To put their offer in perspective, the site says a single dollar, which gets you $25 at a participating restaurant, would only get you a third of a gallon of gas or six eggs out of a dozen, meanwhile your $24 in savings could get you at least a half tank of gas or a full carton of eggs plus cheese, milk, bread and orange juice. And if other businesses ran 90%-off sales, a $120,000 exotic sports car would cost as much as a two-door hybrid, Restaurant.com adds.

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