This deal has ended.
Update: a reader (thanks Kristine!) has provided a new link and this is now valid through 3/14. Arby's is offering a Free Roast Burger with any drink purchase via this printable coupon. I can't say I've tried it, but this appears to be a roast beef / cheeseburger hybrid. The coupon is valid through
3/9 3/14, though it may disappear before then.