I've been using the GPT-3 API in various ways; I occasionally use it through my emacs config as a sort of natural-language abstraction for keyboard macros [0].
I've also been developing a GPT-3 based clinical reference tool [1] -- currently it serves as an exploratory vehicle to see how this technology can be applied reliably to the clinical domain, but as I've started to gain an intuition of the sorts of things it is useful (and accurate) for, I've been using it fairly regularly for quick lookups about particular clinical topics!
[0] https://twitter.com/samarthrawal/status/1591527892386734081