Restaurant.com is offering their $25 certificates for as low as $2 when you use the code SAVE now through November 27th. This means by spending $2 to buy the certificate, you get $25 off your restaurant tab. At this price, I usually buy a few and stock up because they are good for a year.
To maximize your savings, try to choose restaurants that require you spend $35 to use the $25 certificate, which means you will only pay $10 out of pocket at the restaurant (plus tax and tip) and $2 for the certificate. These certificates are a great way to dine out with a family while on a budget.