I second www.instructables.com. Don't forget www.adafruit.com but where I have really found what I need is simply google. If you know what you are looking for

I second www.instructables.com. Don't forget www.adafruit.com but where I have really found what I need is simply google. If you know what you are looking for just use proper search terms and typically there is someone who has already done at least a portion of what I am working on.