Restaurant.com 80% off sale extended
Make sure to read the redemption carefully, however. They vary by restaurant and generally require you to spend above the beyond the certificate amount (like $40 or $50 for a $25 certificate). Alcohol, tax, and tip do not count towards the total, just food. Some restaurants specify days and times you can use the certificates to make sure they aren't overloaded on busy nights.
Caveats: select gift certificates may only be sold for more than $10. Limit of one $25 certificate per visit to a restaurant. This promotion does not apply to previously placed orders and cannot be combined with other promotions or offers.