GPS
My car has a DVD with maps that integrate with the GPS to tell me where I am and how to get where I'm going. I figured there has to be some marine version of this.
I dug this up, with associated chart chips, and I bet there's lots more.
If I were designing such a thing, an auxiliary crank for emergency power (like my flashlights and emergency radio) would be an added feature.
Also, it damn well better float.