I don't have a compass (yet) as I have chrome to buy instead but I have a Formotion clock on my bike, attached to the windscreen, it also has a clamp for the handlebars, but if I remember correctly, they make a compass too..
look at this link, is this what you want?
http://www.formotionproducts.com/compasses.htm
look at this link, is this what you want?
http://www.formotionproducts.com/compasses.htm