I wanted to see how many onions it is possible to host. My internet searches were not yielding any useful results. So I got mkp224o to generate cheap and good looking onions (like "letnot66666..."), which took 2 mins or less with 4 cores and 8 threads.
Then I went to the folder with onion keys, and copied them all. Linux allowed me to directly paste it as a list into Mousepad, which came in handy when using PHP to extract the list and turn it into the right torrc config to go into tor, so Tor knows to try and host 20 sites.
Finally, I did a chmod 700 on the onion directory (via the GUI) so Tor wouldn't complain, and started Tor. I only got a few onions working, but I clicked fast... so did a retry, clicking slower.
All the onions actually worked this time! I shared the news and wrote / edited this blog post... Note that I hosted it for 20-30 mins before shutting down the high performance computer, but the files are intact if I ever want to bring them back online.