I was the lead engineer on an Openwrt router for 2 years at my old job. Their documentation is complete and utter shit, but their design is extremely intuitive. Whenever I said to myself, "hell, let's just try this and see if it works," it had an insanely high success rate.
I didn't know Lua going into this project, but when I left the company, it made me really wonder why more people don't use Lua. It's a really nice language.
I really enjoyed having my own open source router that I could just drop new features into by adding packages and recompiling. I was sad when I had to send all my dev units back.