Some Lutherans, most at our church included, make the sign of the cross at certain points in the liturgy. There are other gestures that are made as well, some by the Pastor and some by us, such as kneeling at the altar to receive the Lord's Body and Blood. There is a good description of these bits of ceremony in Weedon's Blog today. It's interesting, short to read and explains why we do what we do. And why it can never be required, it's a "get to" not a "have to." :-) There is good stuff in the comments section also, so don't miss that part.
Gesture in Worship.