For those of you with LaMar's and Krispy Kremes, those stores are offering a free doughnut of your choice. (I've never been to LaMar's, but I do love their Doughnut Day sign.)
Dunkin Donuts is offering a free doughnut with a beverage purchase. And Tim Horton's has a Facebook coupon good for a free doughnut with any purchase.
Your local doughnut shop may have some goodies too, be sure to call ahead.