Since we emigrated we have used the 2 companies based in the UK quite a lot and would recommend them.
Yoodoo is great to send various cards (very useful on Mothers and Fathers Day as they are on different days over here) and you can add photos and personalise the card and it helps people know you have not forgot about them.
We also use Flowercard based in the Channel Islands to send flower cards to our friends and family. We sent one yesterday to our friend who is getting married on Saturday. The cards are great and an original idea and a different take on sending flowers.