I just submitted to the app store v1 of a Small Craft Motion Program (SCraMP).  Sample screenshots are below.  It's a pretty simple app that draws off the amazing hardware our modern phones have become (seriously, accelerometers, gyro, and non-trivial on-board computing power in a relatively cheap handheld device--it's madness!).  With any luck SCraMP will get accepted by the app store, and hopefully it will do some real good for the small craft and fishing communities.