I tried an app for a very short time and found that this particular app drained the device's battery fast. I am also constantly bumping my phone/tablet which means the app is never zeroed correctly. My current truck has a built in inclinometer, from the factory, which is great and all but I never look at it in tense situations. Maybe the best inclinometer would retain a log of "extreme" angles with GPS coords for review afterwards.
Edit - Hmmm, sounds like a fun project! I already have a GPS connected ras pi running in the truck and a very accurate accelerometer just sitting here. Could merge those together to allow the ras pi to collect logs of angles and lat/lons and then post process said logs into a color coded KML. The KML would not only provide a track of my travels but would color code the track to show angles at a glance. Hmmmm.