UPDATED 11/21 12:15 p.m.: Correcting that iBeer and Pocket First Aid are among the top 10 most popular paid iPhone applications.

Apple’s iPhone has been used for everything from following the 2008 election to deciding where to grab a bite on the go. Now, it’s helping lead-footed drivers avoid costly speeding tickets.

NMobile and Trapster are two mobile applications that provide up-to-date, detailed maps of speed-enforcement zones with live police traps, speed cameras or red-light cameras. After launching, each application pulls up a map pinpointing the locations of speed traps within driving distance. An audio alert will sound as vehicles approach an area tagged as harboring a speed trap.

Both applications rely on the wisdom of the crowds for their data. Users can report camera-rigged stop lights and areas heavily populated with radar-toting police officers through the application or on each company’s Web site. Eagle-eyed motorists using either application can also contribute information on the location of newly spotted speed traps from the road with a couple of taps on the iPhone.

Then, using the iPhone’s GPS location detection, the applications warn drivers when they are approaching known or reported traps.

NMobile and Trapster join the 8,000-plus offerings currently available for download in Apple’s iPhone Application Store, ranging from the practical to the silly.

For example, iBeer, an application that makes use of the smartphone’s accelerometer and sensors to simulate a frothy pint of ale, and Pocket First Aid and CPR Guide, which offers tutorials for treating conditions from snake bites to hypothermia, are both hovering among the 10 most popular paid applications.

For start-up companies like Trapster, the popularity and capabilities of the iPhone has revolutionized the mobile application playing field.

“The game-changer was the iPhone,” said the chief executive and founder, Peter Tenereillo, who saw a significant jump in Trapster’s user base after an iPhone-compatible version of the application was released in October. “We’ve had 100,000 people start using it in the last five weeks.”

Mr. Tenereillo estimates more than 100,000 data points are currently mapped worldwide on Trapster, which is free.

NMobile’s founder, Shannon Atkinson, declined to provide detailed data, though he did estimate that “well over 1,000” users had downloaded the application since it became available last week. (The application, originally priced at $9.99, is dropping to $4.99 Friday morning.)

To thwart false alarms and eliminate inaccuracies, Trapster enlists its community of nearly 200,000 members to rank speed traps on their accuracy. If multiple users confirm the location of a particular speed trap, the icon shows up as red. Less credible locations are colored green.

At NMobile, users submit speed detection hotspots which are then verified against news reports and public records before appearing on the map.

NMobile is only available for the iPhone, though Mr. Atkinson is hoping to expand to additional mobile operating systems, including Google’s Android, Microsoft’s Windows Mobile and Nokia’s Symbian. Trapster is currently available for the iPhone, Research in Motion’s BlackBerry, Nokia smartphones and Windows Mobile.

Messrs. Atkinson and Tenereillo insist they’ve received only positive feedback from law-enforcement officials and police officers regarding their products. “If the application gets people to slow down, I think it’s generally considered to be a good thing,” said Mr. Atkinson.

NMobile is planning to introduce additional features over the next few weeks, including live accident and traffic reports.