Trapster is an app for the iPhone that allows you to view and place alerts for police speed traps, red light cameras, and other related traps. Trapster does use GPS to locate you, but all of the alerts are user generated, meaning you have to trust that the other iPhone users in your area placing alerts correctly or placing them at all.

This app does require GPS, so it's iPhone only. Your best bet is to use 3G as well so you get the alerts nice and fast. You can set the alerts by tapping on the screen to pull up the alert menu. Pick whichever alert you want to set and place it on the map to confirm the trap you've found so other users can be careful. Unfortunately, if you don't have the app open while driving, you're going to miss the chance to place the trap as you can't scroll on the map.

There are plenty of settings that you can change so you can receive voice and vibrate alerts for the traps in your area. The radius you can see around you is only 1 mile, so it's best you keep it set that way. If you actually see other traps listed by users, you can rate their credibility. This apparently will help with making sure you're not freaking out about traps that don't exist.

The idea behind this app is definitely interesting and useful. The issue is, when you rely on user interaction, you may not always get the best results. How many people are honestly going to turn off their music so they can hear the alerts that they pass by? Better yet, how many are actually going to mark down that they passed a speed trap on the app? Remember, you can't scroll around on the app so you have to pull it out and do it fast or you'll miss it! Great concept, it just doesn't work on the iPhone.