There are available (not sure which ones though) ISP's that you sign up for a worldwide account with and they give you a list of "local" phone numbers for either all countries, or each country you stipulate.
Haven't actually seen these, but heard about them...
We use aol because it has local access numbers in most countries and we can usually get them via the gsm fone ( Cannot afford a satelllite jobbie) at local rates. PBO published a couple of articles on this about last April - May. If you cannot find them, message me and I'll send you copies.
I use a local ISP in holland (12move) and else where dial back to england, using Voda, either way is expensive as local calls are about 60p per min + vat and back to england not much more, using their international call "saver"???
Hopefully when the oftell have done their investigations call charges will reflect the true cost as apparently nearly a qtr of vodas profits come from roaming.
Have not found a telco in NL that allows data on pre pay yet, but if any one knows please let me know.
Even if you can get a local sim card that allows connection of your mobile phone to the local phone number of (say) AOL, you will find the cost very high because of the slow download speed. E mail is feasible, but I find internet surfing impossibly expensive.
Best solution is an internet cafe, since most of them have high speen connections anyway. just make sure to empty the temporary internet memory when you finish if you have been doing anything confidential.
Cant comment about exotica such as satellite links etc.
Cruising between Toronto and Charleston SC we use AOL with its local access numbers. While anchored or tied up at a marina I take the laptop ashore and find a phone line to plug in. Many marinas & dockmasters have a line for internet use by cruisers, e.g. Annapolis MD, Hampton VA, Beaufort NC. It's good for email, but not for the web if other sailors are waiting in the dockside queue for the line. I believe AOL also provides email access via its website, which can be accessed at cybercafes or public libraries, but haven't tried that.