There are some interesting music tests on the site below. This one tests for how accurate your pitch hearing is. (Be prepared for very small musical intervals.)
It got me more interested in listening to microtonal music to see if it could help train my ears to hear small pitch differences better. If you look up microtonal music on a site like YouTube there will be some examples. I’ve been listening to a lot of it lately.
If anyone is interested in microtonal music, here are a few links. I saw one of them again recently and though I would add a few links to the thread.
The 7 Levels of Jazz Harmony video is interesting, especially when it gets into microtones at around 8:52. (I don’t remember if he explains it in the video, but there are 1200 cents per octave.)
Differences between microtones in Persian, Arabic, and Turkish music:
Bach in 4 tunings from the microtonal guitar channel:
Sevish makes some interesting electronic music with microtones:
Some other interesting links:
You might be interested in the work of Nicola Vicentino who invented the Archicembalo in the 16th century to enable quarter comma meantone.
Thanks for the link. That’s great. 
The comment section on one of those led me to Ivan Wyschnegradsky. Preludes IV and V are interesting. It sounds kind of like Scriabin with microtones.
Edit: there’s a lot of Scriabin in this one:
Edit: It looks like he wrote a Manual of Quarter-Tone Harmony that is available here.
I was wondering what someone with perfect pitch would think about microtones, and YouTube happened to show the answer in a related video. (For more background on his perfect pitch ability, see Perfect Pitch and Memory)
I think Star Trek should hire her and put these instrument in the show. 
This TedX talk might interest people with an interest in synesthesia:
This Twitter account might interest people who like microtonal music.
Here’s another interesting one: