[poundwise]

I have used this feature before and enjoy the extra layer of protection it provides. I am not scared of using a card online, it is safer than handing you card to the waiter at a restaurant, but its nice to know that if the company's records were ever breached (which seems to happen a lot) the hackers would only get a number that is worthless to them.

I must admit though, I don't usually do this. Only when I am less familiar with the web site/merchant.

Also, this is not worthwhile if you are creating an account that will receive recurring (automatic or otherwise) charges. For instance, I have a card on-file where I buy online music. They charge my card whenever I buy some songs.