One company I had applied to had a job post that was an empty page. I found that strange and, without thinking, I opened the browser console and the page source to see what's wrong. It was a reflex.
There was text in the source saying: "Congratulations, you just passed the first step. Here's the test". The test for the real job post page was to decode the URL which was in Morse. That was cool.
I received a call from the CTO offering me the job. I said the test was really cool but I had found a job in the meantime. He said there weren't that many applicants.
The job I ended up taking: I was sent a dataset in a `.tar.gz` archive. They scored points just with that.
Small "frictions" like that would nudge most people who would not be happy at your company to do other things. They're small enough that people you would be interested in wouldn't even notice.
One other company (it was an online game I liked but didn't have time to play, so I wanted to write code to play on my behalf and I'd just enjoy the game by proxy. They put their call to apply in their HTTP response headers).
