I plug my satisfaction with IDT (
http://www.idt.net ).
* 5-6 cents/min domestic (depending where you live)
* inexpensive international (7 cents/min to Sweden)
* SIX-SECOND BILLING
* One account is $7.95/month, but you have have as many phone lines associated with that account
Their GlobalCall pre-paid calling card is a pretty good deal, too. But I'm tempted with that CostCo card.
Cheers,
Lawrence