I recently attended a scrapbooking expo and found fun slider cards by Pinecone Press Designs. I bought a pack of "blanks" and made these cards with the Close To My Heart Jubliee paper.
Each card is about a quarter inch thick and has a pull tab on the right. When you pull the tab, the card expands as shown below.
This provides a great place to add a personal note and/or a gift card or other small gift.
How fun is that?