What's a good Android app for tracking my driving habits and maybe saving some money on insurance?

Look, I'm all about saving money, and this USAA DriveSafe app is pretty straightforward. It uses your phone's sensors to track things like hard braking, speeding, and how much you're driving at night. It's not intrusive, runs in the background, and then gives you feedback on your driving habits. The bottom line is, if you drive safely, you get a discount on your USAA insurance premium. I've been using it for six months, and my discount is about $75 a year. That's not a fortune, but it's free money for doing what I should be doing anyway – driving responsibly. Plus, it gives you a heads-up if you're developing bad habits, which is useful for a guy like me who's always on the go. The ROI is solid if you're already with USAA.