Stored CC numbers (a'la Amazon)

Does anybody provide functionality on their site by which a customer can log in, reserve a ticket, and see a list of previous credit cards used for previous transactions (just last 4 digits of course), select a particular card and proceed with the order without re-entering the full cc number (like Amazon's process)?

(this functionality already exists within the Tessitura client)

The only way I can think to do with this with the API is to create a custom procedure that would return the full card number back to the client since all of the checkout methods require the full credit card number. Doing this would raise all kinds of PCI flags that I am not convinced could be resolved so my gut tells me that until there is API functionality to use a customer's payment account ID in the checkout process instead of a full credit card number I won't be able to do this. 

of course I could just be ignorant of some already existing methods to do this.

Thanks!