Line2 also turns the iPhone into a dual-mode phone. That is, it can make and receive calls either using either the AT&T airwaves as usual, or -- now this is the best part -- over the Internet. Any time you're in a wireless hot spot, Line2 places its calls over Wi-Fi instead of AT&T's network.

That's a game-changer. Where, after all, is cellphone reception generally the worst? Right -- indoors. In your house or your office building, precisely where you have Wi-Fi. Line2 in Wi-Fi means rock-solid, confident reception indoors.

Line2 also runs on the iPod Touch. When you're in a Wi-Fi hot spot, your Touch is now a full-blown cellphone, and you don't owe AT&T a penny.