"Because they make you think about the music. And when you're thinking about the music, you aren't hearing it"

-- Alan Watts, more or less

I run a dedicated one on my Mac, cost a few bucks but it's way cooler than anyone that came with a player in the past, although the way it feeds audio into the visualizer using the microphone is pretty weak.

https://www.discobrick.com

Since I do my best to keep one online, to me music visualizers are now online : https://do.adive.in/music/ :)

I thought Digg disappeared. :/

The author mentions a web-based Spotify music visualizer (that actually works!), https://www.kaleidosync.com

Such a nice retro thing :)