Magic Wormhole: https://magic-wormhole.io/
An easy and secure file transfer program.
I use it almost everyday since I discovered it. Author has a very good video on it at pycon-2016: https://www.youtube.com/watch?v=oFrTqQw0_3c
There was this fun little number a couple of years back https://redrocket.club/posts/croc/