The iPhone can teach its users how to perform CPR, show them how to mix a White Russian and allow them to identify any song playing on the radio.

But for some owners of the Apple touch-screen device, the 35,000-plus applications lining the digital shelves of Apple’s App Store are not enough. If you want to use your iPhone as a video camera, send a photo message or hook it up to your laptop to connect to the Internet, there’s no app for that.

Or at least, no official app.

Through the efforts of developers and hobbyists, the Web is teeming with unauthorized applications for the iPhone and the iPod Touch, and there are even some independent online application stores.

However, in order to use these programs, iPhone owners have to “jailbreak” their device  downloading a bit of software that bypasses Apple’s restrictions and allows the installation of unsanctioned third-party programs.