* Having extreme fluency in one data wrangling tool for text and tabular data. Could be bash + awk + grep/sed/cut and other shell tools, Python + numPy, Ruby, etc. The point being that given a table or a text file you should be able to extract whatever information you want quickly without thinking.
* Fluency in Postgres, specifically its aggregate functions, window functions, and CTAs. Again, given a company's dataset you should be able to write complex queries to answer business-critical questions in a few minutes to be able to drive decisions. As an aside, knowing that UNIX system usually has sqlite installed and is the fastest way to analyze local tabular data.
* Being a competent writer. Some people command clear thinking, gravitas, and vision when they write. It is easily the most important skill when remote working, and a definite shibboleth when you want to sound convincing to overeducated knowledge workers. Being able to explain complex topics to a lay audience had gotten me many jobs.
* Knowing how to use AdWords, Google Trends and mailing lists to quickly validate product ideas. This is one of the easiest ways to discard or validate ideas. It's so useful and quick and such a simple way to avoid months of wasteful work.
* Knowing the basics of Western philosophy and psychology. Everything humans do fits within a system of values a loosely consistent logics. 99% of people rarely think outside of those value systems, and if you understand the history of philosophy you'll see that we're quite predictable in our wants and desires. It helps you be more persuasive, choose the right work for your own preferences, put people to work where they'll feel useful and fulfilled, and will help you see the pitfalls of certain group dynamics for whatever institution you're working for.
