Dunkin Donuts recently held a terrific integrated online contest to celebrate National Donut Day.

The chain tweeted its offer of a free donut with a beverage purchase to its 83,000 followers and put the offer on its Facebook Page, which has 3.5 million fans.

Then, to keep the donut party going, DD launched a trivia contest the same day, with the winner getting $50 Dunkin Donuts gift cards. Sample question: “Which country sells these Smiley Donuts? Russia, Peru or Puerto Rico?”

Customer engagement needs to be a company-wide strategy to be effective and DD knows how to do it right. Keep it light, engage people, and offer free product. As we’re seeing more and more, Facebook and Twitter campaigns offer fast, easy (and free) channels to get messages to people fast and get them talking.

The next time you’re thinking about an online campaign, take some tips from Dunkin Donuts (oh, and don’t forget to call us!).