If anyone is looking for something a bit more original than the usual...
Moonpig.com could be the answer. I was recommended them when we lived abroad, and had no access to English text cards.
For anyone who hasn't used them before, they have literally hundreds of cards available for every occasion - you select your card, its size, font etc. The text of the card can be personalised to your requirements, and if you wish, you can add your downloaded usual 'sign off'. Also great if you have forgotten to send a card - order online before 2pm and card should be there by next morning.
Even if you don't want to send a card right now, flicking through their range should put a smile on your face!
Combine this with Littleterrors postinghttp://www.hotukdeals.com/forums/showthread.php?p=323279