With the personalised cards depending on the style you can edit the name, age and/or add a photo. Also delivery is FREE so its no more expensive then purchasing a hallmark card in store.
Here is Miss S's card for this year. She is very much a little princess! You can get this design HERE. I got to add her name, castle name, date of birth & her age.
For kids i also like to add couple of sheets of stickers to their cards. It makes opening the card a little more exciting and its particularly good if you're posting just a card to someone as no extra postage is required. I have a range of sticker pads which you can get at reject shop, red dot etc for around $2.