Arduino Cookbook by Michael Margolis

Programming Interactivity:  A Designer’s Guide to Processing, Arduino, and Openframeworks (published July 28, 2009) by Joshua Nobel

• Practical C Programming by Steve Oualline (O’Reilly)
• A Book on C by Al Kelley and Ira Pohl (Addison-Wesley)

The C Programming Language by Brian W. Kernighan and Dennis M. Ritchie(Prentice Hall)

• Make: Electronics by Charles Platt (O’Reilly)
• Getting Started in Electronics by Forrest Mims (Master Publishing)
• Physical Computing by Dan O’Sullivan and Tom Igoe (Cengage)
• Practical Electronics for Inventors by Paul Scherz (McGraw-Hill)

Tinkering with Arduino by Nick Weldin