You can now pay with any altcoin that ShapeShift.io offers.
As of this date that is 36 altcoins.
How to pay with altcoins using ShapeShift:
* During checkout, place order with bitcoin as payment currency.
* On the payment page, click “Pay with Altcoins”.
* Chose which altcoin you want to pay with and click submit.
* Send the amount requested to the deposit address.
Order will complete when payment is received from ShapeShift.