This is a great tool to help organise your wedding. I found the online RSVP service fantastic, saves on postage stamps. I love that you have have more than 1 event for people to RSVP to and you can enter extra questions to ask (like special dietary requirements or number of children attending). The design options are great as well. It is an American site but I paid using paypal and had no problems, I highly recommend it to anyone.

Approximate cost: $10p/m