This is very cool. You go to Hellmann's Facebook fan page and join. Then you make, or have it made for you, your perfect sandwich. Once it's made you 'swap' with 7 people on your facebook page and Hellmann's donates 7 lunches to Feeding America.
Then when you've completed that you can sign up to enter a giveaway for $250 grocery gift card. You can do this every day too so in a week you can have almost 50 lunches donated to Feeding America just for playing on Facebook!
When it's all over they take you to a coupon page to print your own $1/2 Hellmann's products 22oz or larger. I'd say that a pretty good deal.