Step On It

Idea #4.  Another in the series of one dollar ideas.  Or maybe in this case a $.99 app idea.
You've probably seen TV commercials for all the new cars with features like blind spot alerts, automatic stopping if it senses an object in front of you, back up cameras that warn you if something is behind you and lane change warnings.  I think cars need a feature that alerts you when you're texting at a stop light, that the light has changed to green and it's time to get moving.  This would eliminate the need for horn honking. 
It could be an app on your phone that turns the screen green when you need to get going.  This phone alert is ideal since it's likely your phone that's distracting you.  Maybe the audio warning could be a horn honking.  It would be like that app that some have on their phones that knows when you're driving and silences your texts or sends a message to your texting partners that you're not available.
Another feature, connected to your cars sensors, could be an alert when you are driving in the passing lane and not passing anybody or when there is someone behind you wanting to pass or you're being passed on the right (what should be a clear signal that you are in the wrong lane).  This would be called the Autobahn feature since in Europe they would blow you off the road for cruising in the passing lane.