Here are some useful articles on electronics and microcontrollers.
Digital I/O expansion methods.
With the ADXL345 acellerometer you can detect up to 16g! You can also find out how to use it for tap detection and more.
Arduino Interrupt Tutorial: Find out how many external there are on an Arduino Uno - The answer is more than two!
Switch debounce: Three different ways to debounce input push switches with one amazing method that you can't miss.
A tutorial on using the ADS1115 precision 16 bit ADC for low power use.
ESP8266 Webserver: This code shows you how to use lua to create a webserver using html button inputs to contrtol an LED on the ESP module.
How to flash nodemcu firmware into a ESP8266 so you can use the LUA scripting language.