The very simplest of cards - great when you've forgotten to make one for your nearest and dearest (oops!)
For this one, print the card of your choice onto quality white card. I've used a smooth matt card here which is 290gsm (from Mad about Cards) - this gives an excellent print quality and is a great weight for this.
Crease the card with an embossing tool or bone folder, then fold. I like to cut the card when it's folded to make sure that the two sides match up perfect (you'll need a lovely sharp craft knife for this).
You could also try embellishing the card with glitter glues for an extra special finish.