The Tiffany blue and Chocolate Brown card box in the center was just featured on Dream Weddings. The card boxes, which are each hand made, are sold on eBay for $60 or so. This particular seller also makes guest books to match which are stunning. I like these as a more modern version of the mail box, wishing well or bird cage card holders.

Personally, I would place this on the gift table at the reception. This gives the guests a great place to leave their cards and keeps the gift table from looking to empty as the guests begin to arrive. You could also place this on the guest book table, on the cake table, on the escort card table, etc.