If you currently have a data unlimited plan, you can now use your Iphone as a 3g modem for your laptop. Here's how
From your safari browser on the iphone, Navigate to
http://help.benm.at/il.php, select your carrier to download the file. Once downloaded run the file.
After the install reboot your phone, go to settings>general>network and turn on tethering. To tether, plug your Iphone's USB cable into your laptop. If you have bluetooth on your laptop, you can configure a bluetooth modem connection as well.