If you go to the restaurant.com website and use the code SURPRISE when you check out, you can save an additional 80%. That means you'll pay $2 for a $25 gift certificate or $4 for a $50 gift certificate.
The site has a search function, so you can look for restaurants in your area, or in other major cities nationwide.
There are some limitations on the gift certificates, like minimum purchase amounts or days of the week when you can use them, so make sure you read the fine print.
After you use your gift certificate, you'll receive an email asking you to rate the restaurant.
I have signed up and have received no unwanted spam from this site. But, as always, you can give them a gmail or other account, that you use exclusively for savings offers, so that unwanted items don't clutter your work or personal account.
This offer expires on November 24, 2008.
Thanks to the guys at cheapstingybargains.com for bringing this tip to our attention!