Let the hive mind of Engadget get that for you.
"As someone who doesn't reside in the USA, I was wondering what would be the best way to get internet for my computer in the US for a couple of weeks? If it were Europe I know I'd look for some prepaid data. Is there anything similar offered by American carriers? A MiFi or a data SIM that I can tether from would work, but I'm trying to maintain a tight budget. Help!"
What we really want is a cheap web browser to go. Not an ultra-tiny Windows XP PC. A big screen with a simple processor (say 200-700 Mhz) with embedded Linux (Or Windows if Microsoft still wants in this deal) and WiFi support would probably do really well.