Here is a card using a Z fold, all folded from one sheet of paper:
Holiday Tag Team by Carolynn at Splitcoaststampers
(A post or two ahead of this upload in my gallery shows how it stands, the inside, etc.)
It is also a "Trifold Angled" card - for the cut (the cut comes at a point so that you can make two cards from one 8 1/2 x 11 sheet of paper.
Another card using the "Z" fold (sometimes also called the accordion fold) - these ones made from two index cards:
Index card divider accordion card by Carolynn at Splitcoaststampers
Here are the fronts:
Index card divider accordion card by Carolynn at Splitcoaststampers
They are used using the technique Mopzsix already explained (i.e. attached together in the overlapping center panel of each index card)
Hope these are of interest! Happy creating.