If you’re worried of speed traps and red light cameras, this’s probably the site you’d want to checkout before thinking of hitting the road. SpeedTrap.org is sponsored by National Motorists Association, and lists speed traps installed by the state, and also red light cameras. The site’s just gone full public so expect things to be a little messy, as testing suggests that the Google Maps aren’t too precise.
Where SpeedTrap.org is limited, Trapster works just fine, as it provides speed trap info on the mobile, using GPS. SpeedTrap would be a more reliable service indeed, if it added this option as well.