I have had a lot of trouble posting this! Sorry it took so long. I also hadn't meant to post so many pictures, but when I had re-write the post, I kept finding more I really liked! So, here it is! Hopefully...
I got this postcard from Esra in California. I love the picture! She took it on a trip to Bolivia.
I recently found some vintage letterheads online that you can print out. I thought they were pretty cool, and have printed out a few to use, on half-sheets of paper.
The first is this V-mail stationary, used by soldiers during WWII to send letters back home.
From the blog Everyday Correspondence, here are a few of my favorite letterheads:
Another archive of letters I found, is Letterheady. There are some really cool letterheads there, however these images are not free of copyright. I imagine that it would be okay to print out a couple for personal use, though. Some of my favorites: