iTrackMotion
This app allows you to analyse the path of a moving object by tapping out the path of the object in a video.
You can take video from within the app or import video from the camera roll on your iPhone/iPod/iPad.
Each tap marks the point on the screen and then moves to the next video frame.
The app lets you set the scale (in whatever units you like) and origin point from screen touches.
When finished iTrackMotion saves the data to a csv file (spreadsheet file, that can be opened in numbers, excel, openOffice and many other programs). Graphs of the objects path and x and y positions against time are also generated.
The csv file and graphs can then be emailed to you for more extensive analysis.
iTrackMotion is the best thing out there for fast, accurate, intuitive to use, and easy to share motion analysis.