Use Wi-Fi to Make Calls

Most people know their phones have Wi-Fi connections. But many still don't know the Wi-Fi connection can be used to make calls, even if the sound quality isn't always good.

But who's to argue with the fact that the calls are free? This can be pretty useful in areas where your carrier has little or no coverage. For example T-Mobile's UMA -- for Unlicensed Mobile Access -- works pretty well in South Korea, where the company has less coverage.

The catch is that you need a Wi-Fi connection that is pretty robust, and possibly an “unlocked” phone, though that is easier these days now that Apple sells them. At a minimum, it's handy for texting and avoiding those data roaming charges.