The official Hour of Code website - http://hourofcode.com/us/resources - has lots of resources to introduce hour of code week such as videos, posters and hand outs.
Code.org
Code.org - http://code.org/ - Has lots of tutorials for hour of code including creating a winter wonderland with Anna & Elsa from Frozen.
TouchDevelop
TouchDevelop - https://www.touchdevelop.com/hourofcode2 - Has a selection of step-by-step tutorials for hour of code to teach students how to create their own Windows Store apps including a version of Flappy Bird.
TouchDevelop.weebly.com
More hour of code tutorials for TouchDevelop, from yours truly, including the original Flappy Bird tutorial (All in a Flap) and Tap a Mole: http://touchdevelop.weebly.com/hour-of-code-2.html Also check out my festive 8-bit Pixel Art challenge: http://touchdevelop.weebly.com/hour-of-code.html
Khan Academy
Khan Academy - https://www.khanacademy.org/hourofcode - has a selection of video tutorials for hour of code week suitable for students, teachers and parents.
An Hour of Python
An Hour of Python - https://hourofpython.com/ - has a collection of tutorials to introduce programming in Python using the turtle module.
Code Academy (Hour of Code)
Code Academy - http://www.codecademy.com/goals/hour-of-code - gives students the chance to learn JavaScript by creating an interactive animation.
Raspberry Pi.org
Raspberry Pi.org - http://www.raspberrypi.org/hour-of-code-dec-2014/ - has some great activities for the Raspberry Pi for hour of code including Carrie Anne’s popular Turtle Snowflake tutorial and my very own Harry Potter Sorting Hat challenge.
YouthSpark
The Microsoft YouthSpark hub - http://www.microsoft.com/about/corporatecitizenship/en-us/youthspark/youthsparkhub/hourofcode/ - has links to a number of hour of code resources including TouchDevelop and Kodu.
Tynker
Tynker - http://www.tynker.com/hour-of-code/ - contains a variety of puzzles and activities designed to teach students computational thinking skills and the basics of computer programming.
App Inventor
App Inventor - http://appinventor.mit.edu/explore/hour-of-code.html - has a selection of tutorials for hour of code to teach students how to create their very own android apps.
Lightbot
Lightbot - http://lightbot.com/hocflash.html - A version of the popular Lightbot app designed for hour of code.
Scratch
Scratch - http://scratch.mit.edu/studios/283340/ - has a compilation of scratch projects to be used for hour of code.
Scratch Jr
Scratch Jr - http://www.scratchjr.org/teach.html - has a selection of downloadable tutorials to be used with their app for hour of code.
Have I missed anything?
Please let me know if I’ve missed out any hour of code tutorials and I’ll add it to the list!