Earlier quoted context omitted.
I just took a look. Nice looking site, by the way :-) I have the same issue at signup as the GP - I find myself rather unsure what categories make sense for me on your signup page. Similar to the GP, a mixture of embedded, servers, and webdev, except I wouldn't say I do just industrial. Feel free to look at my LinkedIn profile (the link is in my HN profile) if you think it could give you some ideas for additional cat…
Based on your skills, I would suggest choosing the Javascript and System/Devops categories.
Though I think that, on the face of it, completely leaves out my interest in compilers, programming languages and toolchains, and in kernels/devices/embedded systems, which are a big part of my work in practice.
Maybe the "System" in "System/Devops" covers that, but those two are a peculiar match: I've might quite a few devops workers who consider software development to be slightly outside their knowledge, and something like C or C++ programming to be "very advanced". I find it peculiar that anyone can do devops without being a competent programmer but hey, it takes all sorts!