Though $7.99 seems steep for an app, not only does this one allow you to edit Office documents (same as Pages, Keynote, & Numbers), but it also lets you work on Google Docs.
The lite, free, version of this web service lets you create presentations and import them from either PowerPoint or Google Docs. There is also an iPad/iPhone app.
I sent this link to Chris Harrow, a colleague who teaches math at The Westminster School in Atlanta. Here are his first impressions:
Cool = very smooth functionality on the iPad, you can do all the explorations in the most excellent iPad touchscreen environment, a very tactile approach to learning geometry.
Frustrating = you have to create the docs elsewhere, on first exploration, I don't see a way to do constructions directly in this app. If a kid gets a good idea that requires additional "stuff" on the construction, s/he may not be able to instantly follow up on intuition.
Any one else want to weigh in?
This may be the coolest Google trick to date! Doctopus runs a script in Google Drive to automate the creation of docs, hangouts, and more, plus creates a grading platform.