Title is wrong, these are "Curl Command-Line Tricks", not command-line tricks in general. Going beyond curl, there is this classic, the entirety of "Star Wars: A New Hope" in glorious ascii:

    telnet towel.blinkenlights.nl

If the domain is not accessible you can see it here:

https://telehack.com/

Prior discussion:

https://news.ycombinator.com/item?id=4630519

https://news.ycombinator.com/item?id=522072