Freebies for Mom posted the following information.
"Sign-up for the free Denny's Rewards program and on Feb. 28 you'll get a coupon for a Free Burger and Fries to use between March 1 and 7. This food freebie is available to the first 500,000 people who register. See that message at the top that says "Register before February 14th, 2010 and we'll email you a very special welcome offer soon." - well I think it's referring to this free burger and fries offer. Watch your inbox for your coupon on February 28 and you can use it starting March 1. Thanks to Coupon Pro for the update on the coupon delivery date.
You'll also get a free Birthday Original Grand Slam on the day of your birthday. And if you're brave enough to face the crowd on Tuesday, February 9, then you will enjoy a free Original Grand Slam (between 6 am and 2pm). "