You're behind the wheel of a family road trip when the kids start with the incessant "Are we there yet?" Your spouse has to go to the bathroom, and you're so hungry you could gnaw on your left arm. It's no wonder you didn't realize you were cruising a few clicks above the speed limit.

Instead of being slapped with a speeding ticket, imagine your GPS warning you of a speed trap about 900 yards up the freeway. This is the concept behind the PhantomALERT, a new service for your existing GPS device that calculates your vehicle's speed and alerts you when approaching a possible speed trap or red light camera with both audible and visual warnings.

This isn't a radar detector; rather, this site contains a downloadable database of more than 3,400 known fixed-camera or radar sites in the U.S. and Canada, plus users can upload additional sites to keep it up to date. This information would then be imported into your GPS's mapping software via its USB cord.

Supported by many GPS manufacturers, such as Garmin, TomTom and Magellan, PhantomALERT data can be downloaded and used for free up to one year, and it costs $24.99 for an annual subscription thereafter (no commitment necessary).

If you don't already own a GPS unit, you can buy the PhantomALERT Road Safety System GPS navigation unit for $199.99, which also includes 12 months of free updates.

On a related note, Trapster is another service that lets you report speed traps using your mobile phone or by calling a toll-free number. The service warns of upcoming speed traps on mobile phones, PDAs, GPS navigation systems and laptops.