I use a service from Budget Dialup -
http://www.budgetdialup.com/html/get.htm

You buy a block of time from them - for as little as $3.95 - and you can use them as a dial-up provider when you are on the road. I have found that they have pretty good coverage - they have had a local number for every place I have tried to use them. I have a dsl provider at home and just wanted a cheap way to do dialups on the road using my laptop from the hotel. I have stayed in one hotel that had free Ethernet connects - that was even better. All the other options I looked at were much more expensive. These guys had the best combination of low entry cost and long term period to use the block of time that you buy.

Chas