There are plenty of possibility that you can make use of parchment craft, just like any other hand made cards. It's the design that you need. What's good and easy for ding parchment craft is that you do not need to know drawing well, you just trace!! So it's easy and anyone can do it. Found a nice design? trace it and make it into parchment card.
Some design are more generic and for some, one look you can tell what occasion it's for. There are also some design that can become the frame, and you can change the text in the center to make it suitable for different occasion. Don't be scare to explore around.
Here are some sample design taken from books on different occasions usage:
