You'd be able to do this if when creating your own record type, you could add functionality to a field to treat it as a website in order to have the one click access to launch the site referenced. That, or allow us to copy an existing type and call it something else - so, let us copy the web login type and I can call it frequent flyer login and add all the other fields I want for a frequent flyer card and still be able to launch the website from my record.

Put the credit card number as one of the fields inside the web login record. For more or lengthier data put them inside the Notes field. That's what I do.