Jane Street is responsible for the Signals and Threads podcast[1], which I always enjoy. They also contribute a lot to the OCaml language, standard libraries, and do a great job of explaining why OCaml is a great language and paradigm. I've learned a lot because of Jane Street's sharings.
I have no connection or interest in Jane Street but this sure gives me a positive impression of the company.
For anyone that did competition math in HS one of the two authors of the main Art of Problem Solving books is also high up at Jane Street, on the trading side. JS sponsors stuff like math prize for girls now.
Obviously there's a potential recruiting benefit to funding contests and posting monthly puzzles and whatnot, but I still think it's a cool vibe that not a lot of other companies have.
I have no connection or interest in Jane Street but this sure gives me a positive impression of the company.
[1] https://signalsandthreads.com/