Usability 
Trapster offers this mobile site which displays the location of policespeed traps, red light and speed cameras and places where traffic officers are hiding. You just enter a zip code or address to see the traps, either as a list or on a Google Mobile Map. The data comes from registered users of Trapster's free Java, S60 3rd Edition or Windows Mobile 5 and 6 applications which let you report a trap with a single key press using location data from the phone's GPS. The application also gives real time alerts when you drive into an area with a trap. If you don't have a compatible phone you can report traps by toll-free number, SMS or by using Jott's voice recognition technology Via: The Phoneboy Blog
6-Mar-2013: Trapster's mobile site now requires a login and the link to search for traps and display trap maps returns an error