App to Toggle Global Data Roaming?

Is there an app or widget that will toggle, and even better display, Global Data Roaming Access?

I'm going on a cruise and will be bouncing between free T-Mobile global data coverage and $15/Mb coverage, sometimes several times a day. Since it just takes one slipup to run up hundreds of dollars in charges, an app that helps would be useful.

What would be really useful would be an app that would automatically turn data off and on depending on whether the carrier was in a T-Mobile free data country. I'd pay serious money for that one.

The best I can find so far is the Curvefish 2G-3G toggle that gets directly to the Mobile networks settings.