This free app provides instant access to the Common Core Standards. Not sure what to do with it, but it could be useful from an administrative/lesson planning stand point.
This is a great app for students doing field research. Not only does it help identify a leaf, but it also puts a variety of information at students fingertips.
Though intended for the iPhone, this app could work on an iPad. It allows you to quickly and easily create a story by taking pictures. If you have a 3G enabled device, it also will geotag the camera roll. Could be great for field trips.