SketchPad+Explorer

Sketchpad Explorer is a free app for the iPad available at the Apple App Store that allows you to view and interact with Sketchpad documents, called sketches.

Once a sketch is open in Sketchpad Explorer, you will be able to drag objects and select buttons just like you would in Sketchpad. In addition, there are three buttons at the bottom right of the screen.

They allow you to get information about the app, temporarily magnify a region of the sketch and access saved and sample sketches respectively. You can transfer sketches using File Sharing in iTunes, using email attachments, using links in web pages or using services like Dropbox (see the link below for more details).

Use two fingers to pan and zoom a sketch.

The webpage, @http://www.dynamicgeometry.com/General_Resources/Sketchpad_Explorer_for_iPad.html, outlines the various features of the app. Among the cooler features is the ability to:
 * flick a parameter value up or down,
 * replace an image in a sketch with one of your own,
 * shake the iPad to erase traces,
 * change the magnified region and to interact with it with a second finger, and
 * display touch indicators for demonstration purposes.