One time someone tapped into my account and purchased about $20 of software. Fortunately I caught it quickly and Apple refunded the money, but I really don't trust having portable devices or cell phones have access to a real credit card.
That is a good use of a prepaid Visa card. We hear more and more of payment data being compromised.
The prepaid card was great. The debit card isn't as good, because it attaches to ones checking account. With the prepaid, I took money out of the bank in person and put the cash on the prepaid. Paying with that divulged no personal information.
The only reason I stopped using the prepaid is that it added so many fees and wanted so much more information that it defeated its own purpose.