[eCa]

I always [1] use a virtual credit card [2]. It's only possible for the merchant to charge a specified amount during a specified time.

I create a new card for every purchase, but long standing relationships (ie my VPS provider) gets a longer lasting card so I don't have to update it every month.

[1] The only time I ever enter my true CC is when bying something that requires a physical card (some airlines, certain tickets).

[2] similar to http://www.visaeurope.com/en/cardholders/virtual_cards.aspx but branded by my bank

[tezza]

I use a virtual card when I don't trust a merchant / service too.

But the markup ... say EntroPay of 3.5% makes regular usage very expensive.