All these apps are about tons of things you are able to use for students' own learning. Teacher is really becoming a facilitator of students' independent ( or group/partner) learning when the students have all those apps avalable to them. Some of iPad apps I looked at were "convert" which we in physics need and use so often. While it is good to teach the students how to convert units of measuements manually at the beginning of the course, in a higher level of physics assignments your goal is to reach the result and that is when you need your "converter" to operate your data fast and get the desiresd outcome to be discussed in the conclusion.
The other was a "lab timer" whis is also a handy tool in labs experiments. It is so convenient when you have different tools(equipment) avalable to you in one piece instead of many while conducting the labs.