Hi Diane, I once saw a bar that was covered in playing cards and then epoxy was poured over them for a solid clear surface. It looked really cool!
I recently saw a wreath made out of playing cards. I think it strictly used hearts, for Valentine's Day! I thought that was really neat.
Relies brand. Bicycle cards are great for spackling a hole or Inserting putty. You put the spackle in, and scrape. Voila, smooth as silk. These work 10× better than index cards. And if you wash them, you can get more than 10 scrapes per card. & As long as you aren't a maniac with putty, screwing holes in the wrong places, and moving picture frames and mirrors, you get material savings in sandpaper every 3 to 5 years of 100 holes per year or less. Granted a Carpenter or Painter would use a Sharpened Board instead, but for around the Home filling and repairing those occasional loose screws and nails behind mirrors and photos, a used card is good enough.
As far as decor, as others I too have seen these in bars and game-rooms. Just Glue and laminate. You can in a Mancave or FemCave or Poker Room actually Glue 4 or 5 Poker Hands and the entire Deck remaining to Pane1 of a Double Paned Shadow Box and place in behind pane1 Green Felt and Voila when you insert Pane2 atop to keep out the Dust it looks like a Poker Table rather than a Plain Shadowbox with LEDs on the Wall. Inserting a Clock mechanism inside that LED Shadowbox To make that into a more Portable decor usable anywhere is simple as you just accomodate that with 4 poker hands 5 Card Draw and place the Card 3 @ 3 Card 8 @6 Card 13@9 and Card 18 @ 12. It is an easy craft.
If you don't mind cutting them you can punch holes in the top two corners, string several together and make a bunting banner for party decor, you can punch a single hole in the top, tie a ribbon to it and use them as gift tags or bookmarks. You could even frame a set of them for a cool series of wall art.