You're headed to the beach with the boys and the traffic is obscene. Everyone is headed in the same direction because everyone uses Google Maps - seriously, this is a real problem that's described in Nate Silver's The Signal and the Noise. Enter Waze - this handy little app will give you the fastest backroads to travel and shave hours off your ETA. On my last beach trip, my brother used it and we hit the beach 30 minutes before the Google Maps expectation.
The UI on Waze is slick and simple - it feels like a cutesier Google Maps. There's no in your face sign up. Waze makes money by cleverly putting in place product ads that aren't intrusive. If you're driving by a McDonalds, for example, a little McDonalds notification will flash for a few seconds (which, depending on your perspective, could be pretty useful).
Oh, and one more thing - Waze was acquired by Google in 2013, so you have the security blanket of being in the hands of the best engineers in the business.
While I can't promise you that it will lift all the cars into the air and allow you to pass through traffic as you wish, it's definitely worth checking out for 2 more reasons. Waze encourages it's users to share information that people come across while on the road. So for instance if there is a cop car hidden off the road or a mattress that flew off someone's car and is now in the middle of the highway, people notify the app and then you get alerts about it! It's genius. One of the best ways I know of to win the road over cops.