ScreenCaptCoord (was MouseCoord) shows the current coordinates of the mouse cursor.
It can draw a rectangle or an oval (see FAQ) to measure the pixels on the screen. It is intended to work with magnification software, such as Pixie, which is included in Apple's Developer tools, or others (Macnifier, etc.).
It can take screen captures and edit them (resize, crop). It can display the ASCII code of a key and its name (US keyboard).