Though an older post, this is still a good starting point for integrating QR codes into the classroom. The Mobile Native is a great blog for integrating mobile devices and focuses on younger students.
Polleverywhere is an amazing tool to use in the classroom and works on any device. However, in the past, it was difficult to create and disseminate polls from the iPad. This blog posts describes the new Mobile Presenter tool.
This is one app that almost fully replicates the online version. The mobile version of VoiceThread leverages the built-in capabilities of the device to easily create new projects.
"Mobile Learning SIGSIGML is the ISTE special interest group that is an advocate for mobile learning worldwide, and promotes meaningful integration of mobile devices in teaching and learning in formal and informal learning environments." - from SIGML
Another great digital storytelling app, there is a free version as well as an enhanced service. With the free app, you can create and share stories with images and audio straight from your mobile device
"The debate over digital learning will soon enter a new phase. No longer will educators debate whether or not digital learning has the capacity to transform the American education system. Just about gone are the anti-technology Luddites who insist that every classroom be self-contained, with students and teachers left to their own devices, save for the help of pencils, chalk, blackboards and weighty textbooks stuffed into 10 kilo backpacks." - from ISTE about the need for the new Mobile Learning Group.
What Did We Do Today? (WDWT) is a mobile platform for sharing class events with teachers, parents, and students to track assignments, reminders, homework, etc.
Flashcard Exchange works much like Quizlet but with a slightly cleaner interface. Students can create flashcards with images or their own text and then test themselves. Flashcards can be published and shared as well. It does work with some apps for review on mobile devices.
This is a great blog from a group of educators in Texas. They have written a few good articles about iPad deployment as well as mobile technologies in the classroom.