Go to the craft store and find either those heavy paper(like cardboard) boxes or the inexpensive lightweight wooden ones. Paint or stain to taste, decoupage either one or a combination of cards on each. They would make great presents for family members. Kinda like Christmas memory boxes. Bet Hat boxes would work too. Really neat find!

I like to use the vintage cards for lampshades. I've included a link below. It's fun to swap them in during the holidays.

I've also used them for art on glass blocks. Just scan them and resize or crop to fit or put a solid color background behind.
{{!gwi}}

Here is a link that might be useful: {{!gwi}}

Those are all good ideas. I especially like the box idea and the lampshade.

How about putting the smaller ones in between two pieces of glass and then soldering the edges....makes really nice coasters.