Not only does BaiBoard allow students to collaborate on a shared whiteboard via their iPads, but they can also jointly annotate PDFs. Much like with AirSketch, BaiBoard also includes the ability to do a web share. This means that when on the same network, and with the unique URL associated with the iPad, ANY device can see a student working on their BaiBoard through a browser.
YouTube's response to Vine & Instagram, MixBit allows you to shoot, edit, and post video from your mobile device. Technically an iPhone/iPod app, it would work on iPad.
allows presentations to be uploaded to a free teacher account (PPTx or PDF and only 2 at a time) that can be viewed on any device when a presentation is live.
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.
Platform similar to SubText that allows teachers to publish PDF, ePub, Word and Excel & classes / students can read collaboratively on any device. Documents are published using HTML5 = iPad friendly.