Great blog by J Bergmann @ Turning Learning on Its Head with step by step video tutorials on how to use a combination of Google Drive (free) and Explain Everything ($2.99 in App Store) to flip the class.
Explain Everything is an easy-to-use design, screencasting, and interactive whiteboard tool that lets you annotate, animate, narrate, import, and export almost anything to and from almost anywhere.
Create slides, draw in any color, add shapes, add text, and use a laser pointer. Rotate, move, scale, copy, paste, clone, and lock any object added to the stage.
Add new or existing photos and videos. Import PDF, PPT, DOC, XLS, Keynote, Pages, Numbers, and RTF files from Evernote, Dropbox, Box, GDrive, WebDAV, Email, iTunes, and any app that allows you to open these files types using “Open In…”. Export MP4 movies, PDF documents, PNG images, or XPL project files directly from your iPad.
Go to the full blog with instructions on how to set up Google Drive and upload to it as well.