Waze — free GPS "social navigation" app

I badly want Waze to be a success because the idea is just so perfect: a free navigation app that integrates user-generated traffic information. So, you're stuck in traffic someplace, you whip our your iPhone, and let the world know that they ought to take a different route if they're traveling the same road that you are. It's a wonderful example of crowdsourcing. The trick is to get lots of people to use it. And increasingly people are. But if you live someplace where there's not much coverage, the app has less value than other places where it's really caught on. You can also use Waze to alert others to police traps, construction, speed cams — that sort of thing. Waze's features include constantly updated road maps, turn-by-turn directions, real-time traffic updates, automatic rerouting, and more.