Here are some useful articles on electronics and microcontrollers.
Digital I/O expansion methods.
How to use MC78M05BDTRKG for maximum current without using too large a heatsink pad and how to select the optimum input voltage.
How to use fixed point maths to save microcontroller memory by avoiding use of the floating point library.
Essential Guide to the DHT22/11 humidity sensor with library code guide and Full Arduino Tutorial. Learn how to Easily determine Humidity, Dew point and Heat Index.
I2C tutorial: Learn all about the 2 wire I2C serial protocol. Learn how easy it is to use, how it works and when to use it...
The Essential Guide to the 74HC595; What it is and how you can easily use one in any of your projects.
How to Easily Use the DS18B20 Maxim One-Wire thermometer with Arduino example code showing external or parasitic power modes.