A quick search of the archives shows we haven't discussed this company in nearly five years and at the time it was only a wifi/VOIP solution.
This company is offering a SIM card without the roaming charges. The rates are a little steep. It's more expensive than using a local SIM card from the country visited, but it's cheaper than using ones SIM abroad. The subscriber will pay more, but it eliminates the need to play musical chairs with SIM cards.
While it appears to work globally, the cheap rates are only valid in US, UK, and Australia with more countries coming soon. If they could cover all of Europe I think this would be good for someone continually hopping across borders.
Site: