As a frequent traveler, I can tell you that all mobile/WiFi services are not created equal. The best I've found is Boingo. The service is even better than the name. Unlike T-Mobile, you can access it in places like Atlanta Hartsfield airport. $7.95 for mobile WiFi...$9.95 for laptop WiFi (what I use). Unlimited. Like roaming without fees. Hotspots in 100,000 places worldwide. Click
here for Boingo details.