I decided to dig into my stash of SU's DSP, and I created a birthday card for one of my friends. Pinterest has become my "go-to" site for cards with creative folds, and I found several variations on a Z-fold card.
In order to write a birthday greeting, I used SU's Whisper White to create a space for the greeting. Because of the way the card is folded, the greeting is not visible until the card is unfolded.
I entered this card in the Mod Squad Challenge Blog: It's My Favorite