Credit card numbers, expiration dates, and CVV's are all numbers, so why not collect them all in one field and leave the number keypad open the whole time? Good idea, Zachary Forrest. via Luke.
Related: if you use Stripe, that might be literally all you need to collect payment. But other payment processors often require more info (like address) so not collecting that info is dangerous (should you need to switch someday).
And speaking of UI experiments, this is an interesting take on the select menu.