Thanks for the replies. Prepaid seems the way to go and in addition to maglobe
http://www.maglobe.com/ I see that AT&T
http://www.consumer.att.com/prepaidcard/cu.html and budget dialup
http://www.budgetdialup.com/ offer similar services. The crucial bit is the 800 number (you can always fall back to a cheaper local number if there is one).
Happy new year everyone!