Digital tools that can help Personalize and Differentiate

I gave a presentation this past weekend in North carolina to a group of dynamic librarians, about how to fill their digital toolbox. I've posted the handouts and slides over on our blog:

http://differentiatedinstruction.co/2013/02/04/using-digital-tools-to-en...

I hope you might find these tools useful as well.

What are your favorite digital tools to help engage kids and let each demonstrate their mastery of the lessons and subject matter? Do you use any of the ones i suggest, and what's been your experience?