This is the Birthday card I made for my husband. Eight small origami envelopes, mounted on a piece of A5 card.
I got the idea from here, and there's even a little tutorial over there! The only real change I made was a small piece of double sided sticky tape to hold the "diamond" down to help keep them closed and keep their form.
The great thing about this design, is you can slip little messages inside each envelope - it's like getting loads of cards in one!