For me the original plan was bilingual (English/Japanese) plus engineering but I ended up getting more career mileage out of being able to program rings around most SaaS companies' marketing teams. (A high bar that is not.)
You can pick many, many things here, though. Combining programming (any stack which lets you ship things) plus any other white collar profession works well, too. Try embedding in anybody's workday and just sit on your hands and watch the insanity as they do any data-processing work, for example. It's insane how much of day-to-day accounting work exists because of the lack of 50 lines of Ruby.
In my experience I've found that you can automate a lot of white collar work if the rest of the business will become organized enough to make that happen. If they aren't collecting or ingesting the right data already, then the hard part is changing their behavior, not writing the code.
Let's say, a coder with significant law knowledge, such that he knows more about law than all the other coders and more about code than all the lawyers, in a given company.
I think this is a good example. I would just add that it helps to be able to deflect when the lawyers come to you with all of their technology problems and coders come to you with legal problems (or whatever appropriate mix of skills and problems). You don't want to end up having to fix all the printers.
You can pick many, many things here, though. Combining programming (any stack which lets you ship things) plus any other white collar profession works well, too. Try embedding in anybody's workday and just sit on your hands and watch the insanity as they do any data-processing work, for example. It's insane how much of day-to-day accounting work exists because of the lack of 50 lines of Ruby.