Even though we're walking around with constantly connected smartphones, many of us struggle to get our other devices online. The easiest way (outside of public Wi-Fi) is to tether them to your phone, either via a USB cable or by using the phone to create a Wi-Fi hotspot.
Data tethering is built natively into Android. However, some carriers make that feature difficult to use -- they'd rather have you pay extra to subscribe to their tethering services. As a result, your carrier may not approve of the use of these apps. (Apple definitely doesn't approve; there are no tethering apps in the App Store.)
With one of these six apps, though, you can harness your phone's 3G/4G connection to quickly get your tablet or laptop online.