I think Starfighters was another, a recruiting firm that found talent via coding challenges, for which Patrick built a mock stock exchange with an API for people to write trading bot clients to defeat specific 'levels' of the game. It was a lot of fun.

https://www.starfighters.io/

[Note, as the site is defunct, it appears the TLS certificate hasn't been renewed and so you'll probably get a security warning from Chrome.]

Great guy, transparent with his finances, always giving free advice here and on his blog.

He got a great following on HN, so great that Stripe hired him. :)

Translating and consulting are the other two, presumably.