A MiFi unit (uses 3G data sim) may serve you even better. Whilst the device connects to the 3G network it presents itself to your computers as a wireless hub. No USB ports are required as they are standalone devices (just need to be charged). A little research on frequencies used will allow you to purchase a MiFi unit that will work in many places in the world that have 3G (you will just need to purchase a sim card – prepaid- at these locations.) Look for brands that still present as a wireless unit whilst being charged. Some do not.

Will also work well with the WiFi capabilities of your MAC’s

Paul

We love Skype – using it now – but even just the data sans Skype is wonderful, and we have a cell program on Vodaphone through Carphone Wharehouse which allows call to the US and New Zealand for about six cents US per minute.

Steve

be aware that a number of European 3G operators are blocking or are planning to block VoIP calls as Skype. There is actually an ongoing debate about this issue in several countries.
On the other hand 3G coverage is quite good in the areas you are mentioning, although you will have to fight a little bit to get those tariffs you observed in London:
These days the European Community has issued a future top for data-roaming within CE-land which will be 1EUR per MEGAbyte….
And you can bet that the operators will use this margin.

Hubert