I mentioned this at one of our meetings earlier in the year, but thought it was worth mentioning on the blog as well. It's easy to forget that the iPad has a camera! I admit I completely ignored this function for almost the entirety of my first year using the iPad in the classroom. It's a basic idea, but a camera is a really useful classroom tool!
The primary way I use the camera in the classroom is to take photos of my white-boards. Too often in the past I would have an excellent brainstorming session with my students, only to absent-mindedly forget (or, even more commonly, run out of time) to write things down. The camera is certainly a time-saver in this regard.
I've also taken photos of student poster presentations. Posters are often too bulky to collect and the students sometimes want to keep their efforts for end of the year projects. Taking a photo is a great way to save copies either to grade or to share with future students working on similar projects.
There are two apps that I think really complement the use of the iPad camera in the class room - GeniusScan and Evernote. GeniusScan allows you to easily turn your photo of a white board into a black-and-white clean copy that is worth saving. Evernote is a a more involved note and document compiling system, but it certainly is a nice way to file away those iPad classroom photos!