Going to the Board -

Well, it may not provide mitigating effects to the 'ants in the pants' syndrome they way going to the board does, the ipad can be a great way for all students to be taking a turn at the board simultaneously. I can think of two quick ways to share student work with the class.

Short Work - Whether your playing classroom jeopardy or you ask a quick short answer question, students can quickly draw their answer on the ipad and simply hold it up - like the old slates. They can do this with any of the drawing apps or with the notetaking apps as long as the line width is thick enough to be seen by the whole class.

Slightly Longer Work - Perhaps students are working out a problem or drawing a graph or diagram or writing a short paragraph. These can all be displayed to the class quite quickly by emailing to the projection ipad and opening up the attached pdf or image in photos or the goodreader app. By clicking and holding the image in the email a selection menu will open allowing you to either open the doc in another app (like goodreader) or saving/copying the image. These can then be quickly shared with the class and then deleted from the main projector ipad.