I recently purchased this great vintage screen window that I found in an old garage. The possibilities! The first thing that popped into my head was using it to display old family photos. I tried a couple of different options for attaching them, but found that straight pins worked the best.
I raided my wife's sewing supplies (shhhhh!) and found a bunch like this...
Then I used two needle nose pliers to bend them. I had to make sure to bend them as close as possible to the head of the pins otherwise they kept falling out of the screen.
From there I started poking them through the photos and then through the screen. Remember that you'll be making holes in your photos going this route, so if you want to keep your old photos intact, it may be best to use copies. You could also use other vintage paper ephemera such as postcards as well.
Other ideas are to hang decorative thingamabobs from it. I'm big on using what you have on hand, so I used a clock, vintage hand mirror, antique ceiling tile, and a metal fleur de lis. I used 20 gauge wire to attach it them to the screen. One thing to remember here is to try not to use anything too heavy as over time it will cause the screen to sag.
There are also other options which I didn't try out for lack of time, but florals would be one that I think would look really nice! Or maybe to display vintage textiles such as doilies or handkerchiefs.