Unity3D: A simple script that looks at the target transform - Source: http://wiki.dreamsteep.com/Unity3d

ExecuteInEditMode.js

// Make the script also execute in edit mode.
@script ExecuteInEditMode()

// Just a simple script that looks at the target transform.
var target : Transform;

function Update () {
  if (target)
    transform.LookAt(target);
}