Stoodle is an online collaborative whiteboard service designed by CK12 Foundation. that allows students and teachers to quickly create and collaborate on a virtual whiteboard. They can upload text, images and even turn their microphone on to explain concepts in real time! This would be an excellent group-work site, or great for students collaborating in different schools.
How Teachers Are Integrating Technology into The Common Core from Edudemic. Specifically discusses mobile devices, such as iPad and disruptive (in a good way) technologies such as iBooks and iTunes U. Provides specific examples tied to Common Core.