Execs who roam around the globe need to tell someone besides their admin or secretary where they’re headed if they leave the country. Who needs to know? Their bank.

That’s because many financial institutions that issue credit cards will now place a fraud hold on cards used overseas unless the card holder gives them a heads up about the travel plans.

And if your card gets flagged by your bank anyhow, be prepared to answer a litany of questions from its security folks that could include more than just your mother’s maiden name.

That’s because there’s mounting evidence that social networking sites may be providing info on users to their financial institutions. If you or your relations frequent these sites, your bank may have mined your profile — or the profile of your relatives — to find out more details about you than you’ve ever imagined.

On his blog, security researcher Roger Thompson tells a truly cautionary tale of a recent trip overseas when his credit card got frozen by his bank.

Seems the U.S.-based Thompson never let his bank know he’d be in the U.K., so when he tried to check out of a London hotel, his card couldn’t be processed.

Thompson got on the phone with his bank, Wachovia, to verify that he was in fact the card holder.

That’s when things got weird.

The Wachovia security rep starting grilling him about details of his life Thompson never provided the bank with. Sure, he’d given up his mother’s maiden name to be used as identity verification.

But the security rep on the line starting asking questions about Thompson’s daughter-in-law, someone he’d never told them about — her age and such. The security guy also used her maiden name, despite the fact she’d been married to Thompson’s son for nine years.

Ever the security researcher, he began to ponder where they could have gotten this data. His conclusion: The only place it existed online was Facebook, where his daughter-in-law was his “friend.”

In a follow up to his original post, Thompson wonders this: If everybody’s using Facebook for free, but there are scores of pricey developers writing applications for the site, then how exactly are they getting paid?

The commodity Facebook has to sell is information. Users’ information. Who could blame them if they put a price tag on it?

All those “apps” on Facebook that ask to use your information must be doing something with it. Are the creators of those farms or gardens or quizzes really all that interested in your fertilizer preference or who’d play you in a biopic?