[jamesbritt]

I would want to know that my card type will be accepted before entering the digits.

You don't need a drop-down for that, but the list needs to be someplace, and if it's part of the form it can be a sort of a CRC for user intent if the CC number doesn't pan out. Might make it easier to prompt the user to make a correction.

[uggedal]

Paypal shows icons of all major credit card companies below the credit card number field. When you start typing the non-matching card types gets grayed out.

[jamesbritt]

That is really quite clever.

It's the sort of idea one wants to generalize and steal for other things on a site.

Makes me wonder if there are any sites that showcase or catalog non-trivial/non-obvious UI techniques.

[jrockway]

I have seen some Javascript that adds the logo as soon as you've typed enough digits. I thought it was a nice visual cue that the card type was auto-recognized.

I think the logical improvement to this interface would be to put the credit card type after the number, and then have it be auto-selected. That way the user can select if he wants, but it will be correct by the time he goes to select it.

[Manfred]

Showing a logo or a message is really easy, ie. http://github.com/madrobby/creditcard_js