Ok. Well, since there is more GSM-based coverage than the CDMA based one in the world, if you were to choose from U.S. carriers it would be either Cingular or T-Mobile, but Cingular seems to offer better set of roaming partners. They have something called DataConnect Global, with two options.

Look:

Cingular Laptop International Roaming Plans

DataConnect Global $139.99 per month.**
Take your laptop with you for all of your data needs when you're traveling outside the U.S.. This plan includes:

* Unlimited domestic U.S. data usage.
* Up to 100 MB of data usage per month in the set of DataConnect Global "Select" countries (on select carriers) (Canada/Mexico + other countries in Europe/Asia are included).
* $.005/KB (approximately $5/MB) overage rate in the set of DataConnect Global countries (on select carriers).
* $.0195/KB rate in all other countries where Cingular currently has data roaming agreements.
* Access to UMTS/EDGE/GPRS where available based upon device capability and network capability.
* One year minimum term required for this plan.
* Currently available in select markets.

DataConnect North America $109.99 per month.**
Take your laptop with you for all of your data needs when you're traveling in Canada or Mexico. This plan includes:

* Unlimited domestic U.S. data usage.
* Up to 100 MB of data usage per month in Canada and/or Mexico (on same select Canada and Mexico carriers available with the DataConnect Global plan) $.005/KB (approximately $5/MB) overage rate in Canada and Mexico (on select carriers).
* $.0195/KB rate in all other countries where Cingular currently has data roaming agreements
* Access to UMTS/EDGE/GPRS where available based upon device capability and network capability.
* One year minimum term required for this plan.
* Currently available in select markets.



This roaming agreement includes the most recently deployed 3G coverage in the world (UMTS - aka WCDMA), so this is a pretty good fit I think. I am not sure which countries you will be traveling to the most, so you probably want to check with Cingular if carriers from those countries participate in Cingular data roaming.

Hope this helps. You can reach Cingular @ 1-888-333-6651.