I use Evernote for lots in the classroom. From pics of student work that I dont want carry home, to student conferences, to creating documentation panels.
I Use Khan Academy for quick vid tutorials for children
My district blocks you tube but I sue it on my phone when needed.
I access Google docs to see student work
Ted talks for professional development
Common Core - They are useful to see. Although I am philosophically opposed to the high stakes testing of the current climate