After a lot of searching for good ecard system, trying many and finding a LOT of pretty basic systems I finally found Postcard Direct. It is perfect. The delivery system, logging, administration systems are all robust, easy enough to use. The multi lingual ability, support for various media are all excellent. The only thing I would say is that the templates are a bit basic, but it is easy to integrate into your sites design.
B-) - my site http://www.tribalcog.com/