Nothing serious -- just playing around.
My late wife's Cherokee had an overhead console with a compass function (sort of -- it only reported N - NE - E - SE ... etc, so not very "granular") which I rarely used but nonetheless enjoyed having. I've been looking for an Android app that will give me similar functionality in my Cherokee, along with an accurate speedometer (because the one in my Cherokee is off my about +2 MPH, as tested against a number of those roadside radar trailers to police like to scatter around the countryside).
So far, the only app I've found that gives me what I want (plus altitude, which is a nice plus) is one that's actually made for light aircraft. It also includes an artificial horizon, which makes for a rather busy display. I tested one app that's supposed to work on GPS and claims to report both speed and altitude, and it was a complete failure. Speedo function was intermittent, compass heading wasn't accurate, and I never got an altitude readout.
Does anyone know of a decent compass app that's oriented toward drivers rather than hikers?