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 - http://code.org/ - Has lots of tutorials for hour of code including creating a winter wonderland with Anna & Elsa from Frozen.
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.
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 - 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)
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.
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 - 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 - 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 - http://lightbot.com/hocflash.html - A version of the popular Lightbot app designed for hour of code.
Scratch - http://scratch.mit.edu/studios/283340/ - has a compilation of scratch projects to be used for hour of code.
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!