Useful learning resources

Getting Started With Arduino 3rd Edition by Massimo Banzi and Michael Shiloh
A short and practical guide to the getting started with the Arduino platform. Explains what you might use it for, the principles behind the platform, some basic code and electronics guidance.
Make: Electronics by Charles Platt A very hands on guide to the fundamentals of electronics. Assumes no prior knowledge and uses some great real world examples and practical applications.
Practical Electronics for Inventors 3rd Edition by Paul Scherz and Simon Monk
A more in-depth look at electronics. Very good for those with a grasp on the basic topics.

Learn at Sparkfun
Learn at Adafruit
Kobakant DIY - Lovely guides for DIY e-textiles and conductive material-based components and projects
Arduino Stackexchange - forum for asking questions