Quick References:
Code Cheat-sheet – Link (The Mechatronics Guy)
Arduino Code References – Link (Arduino.cc)
Tutorials / Intros:
Introduction to Arduino PowerPoint Presentation – Link (Sparkfun)
Arduino Tutorials – Link (Arduino.cc)
More Arduino Tutorials – Link (LadyAda)
Even More Tutorials – Link(Makezine)
Example Projects:
Arduino Playroom – Link (Arduino.cc)
Arduino Projects – Link (Hack a Day)
More Projects – Link (Instructables)
Even More Projects – Link (MakeProjects)