Here is a list of things I have used in the past. My criteria for including in this list, is my ability to talk knowledgably about them to an industry proffessional. Everything on these lists I have worked with.
C/C++, Lua, QT, Electrical Engineering, NoSQL, GAE, Jenkins, Computer Vision, HDL (Verilog),
For whatever reason, recruiters are always curious as to what python libraries I am familiar with. Listed here is the complete set of packages that I am familiar with.
argparse, asyncio, cProfile, collections, configparser, contextlib, copy, ctypes, dataclasses, datetime, fnmatch, functools, gc, glob, gzip, hashlib, importlib, inspect, io, itertools, json, keyword, math, mimetypes, multiprocessing, numbers, os, pathlib, pdb, pickle, pipes, pprint, profile, pstats, pwd, pydoc, queue, random, re, secrets, shelve, shutil, socket, sqlite3, struct, subprocess, symbol, sys, telnetlib, threading, time, timeit, traceback, tty, turtle, typing, unicodedata, urllib, uuid, venv, xml, zipfile .
CairoSVG, Cython, PIL, PyVISA, Pygments, beautifulsoup4, boto3, celery, cffi, colorama, django, flask, fuzzywuzzy, imageio, ipython, jinja2, lxml, matplotlib, mock, mrcnn, networkx, nltk, numpy, opencv, pandas, pexpect, piexif, praw, pymediainfo, pyqt4, pyserial, pytz, requests, ring, scikit-learn, selenium, six, snakeviz, tensorflow, tornado, usaaddress, xldr .