Smart phones are an incredible educational tool for both educators and students. I have an Android Smart Phone and I can do pretty much everything with it that I can do on my computer or laptop or tablet. This means that I always have access to my data, files, information, and can do work anywhere. Students have the same ability with their smart phones. They have access to information, class resources, and so much more at any time. Instead of buying a $200 graphing calculator, they can buy a $0.99 app. There are tons of great apps out there for educators and students to use.
Here are some mobile / smart phone apps and resources for students and teachers:
100 Mobile Tools for Teachers - mobile sites and resources for teachers
Android for Education - resources, apps, links, and much more