Mobile phones, and especially smartphones and PDAs, are in fact small computers that have almost all the functionality of a personal computer. Hence, there are many ways to use them apart from just making calls or sending text messages. Of course, many of us use their phones to browse the Web, listen to the music, check e-mail. But there are much more ways to use mobile phones. I have already descried many useful applications in my previous article. Here I want to give some more examples as well as some general tips.

Battery charger for mobile phone. Most phone chargers have an output voltage in the range of 4 - 5 Volts. This is the same as the voltage of three AA or AAA type batteries. One can just use a small flashlight with three AA or AAA batteries to make a portable charger. Just cut off the cable of an old charger and solder it to the contact leads of the flashlight (there are also USB charging cables for some phones, if you can find one, that will be cheaper than using a charger). Notice that bigger D or C type batteries have a much larger capacity, so using them you could charge your phone much better. However a flashlight with such batteries is much bigger and not so convenient to carry, besides it is more difficult to find such a flashlight and batteries.

Flashlight. Ok, I have just described how to use a flashlight to charge mobile phone. But on the other hand, one can use mobile phone as a flashlight. It is sufficient to open an application that makes the biggest part of the screen white (for example, messaging). There are also many freeware applications that make the screen totally white and shining at maximal possible brightness. Such applications can be easily found on the Web.

Storage device. Yes, as most mobile phones have a memory card (SD, MMC, Memory Stick Duo), one can use them just like a flash disk. As almost every laptop can read memory cards, one can just insert the card from the phone and use it as a portable storage device. For desktop PCs one can use a card reader, which is not bigger than a typical flash disk. One could also use a cable or Bluetooth connection but for that in most cases it is necessary to install a special driver.

Webcam. As most phones have a built in camera, they can be used as a webcam. There are some PC applications that turn mobile phone into a webcam (for example, Mobiola). There are also phone applications, like Qik, that make use of the phone's Internet connection, so one can have a mobile webcam that does not need a computer.

Voice recording. And of course, mobile phone is most suitable for voice recording. One can record phone conversations or use it just to make quick voice notes. Voice recording is available in many phones, however it is often not easy to reach it, which makes it impossible to start recording quickly. But some third party programs, like Resco Audio Recorder, have a one-button recording option which allows starting recording immediately by pressing a predefined button.