A gamepad translator (or gamepad mapper, gamepad to keyboard, gamepad to mouse) is a software that takes input from a gamepad and translates it to key strokes or mouse actions.
The main reason why people would use such a program is that they have a computer game that lacks support for gamepad/joystick. By "emulating" a keyboard or a mouse with a gamepad device, the problem is solved. Another approach has been taken by Belkin, the device Nostromo SpeedPad n52 which can act as either a keyboard, mouse, joystick or as a hybrid between the three.