[bob1029]

Zener diodes can be used as the basis for a quantum random number generator.

https://opg.optica.org/optcon/fulltext.cfm?uri=optcon-1-7-15...

[phkahler]

These are also good noise sources and were use in several early video arcade games for producing explosion and spaceship thrust sounds.

https://en.wikipedia.org/wiki/Noise_generator