Restaurant.com frequently does sales on their certificates, but I've never seen 90% off before! It's a 99 hour thing, in honor of today's date- so now is a great time to try them out! $25 certificates cost only $1- what's not to love about that. Just be sure to use code: NINETY when checking out to get your discount.
Of course, there is a bit of fine print so be sure to read that as well. A lot of the $25 certificates require purchases of $35 or $50 (excluding alcohol and taxes) to be used, and some places even add an 18% gratuity based on the pre-discount amount. Still, if you are planning on eating out sometime soon, it's a great way to save a few bucks.