I have an Android phone with an unlimited data plan. I use a tether program from junefabrics.com where you can find other downloads for i phones, blackberries, etc.
You download the programs to your laptop and phone and then link them with the PdaNet icons with a USB/phone cable. It provides good internet access as long as you have 3g or 4g on your phone. It's essentially free after you pay $15 for the download.
I've been using this system for about a year, sometimes I can't get online or I lose my connection, but for the casual traveler, it works and the price is right.