I've seen that a lot of people recommend knowledge of git and regular expressions as must have underrated skills.<p>what are some others that one should have as a developer?
I think "natural languages" are a skill, programmers should have. The more, the better.<p>In my opinion this is really important for documentation, comments, API design, variable/function/classnames, communication with other developers and so on.
Time management. Not only can it help you when dealing with deadlines, it can also help you manage multiple projects at once. Knowing how many hours to put into project A or B each day to still meet goals is pretty important. It can also bleed into your out-of-work life as well. Blocking off time to relax/learn/workout is important to get the most out of your day. It is definitely something I have struggled with but have seen results when actively trying to manage my time.