For drivers who tend to disregard the speed limit and traffic lights, Trapster for iPhone can be a very useful tool.
With Trapster, users can record the locations of speed traps and red light cameras, and be alerted when they are driving towards potential danger zones. Trapster offers real-time data, and claims to be more effective (and legal) than radar detectors, which often alert drivers too little, too late.
Users must register to use Trapster, but it’s free.
Watch a demonstration of Trapster: How Trapster works