Unity3D: Raycast object avoidance - Source: http://wiki.dreamsteep.com/Unity_ai

AvoidObject.js

var target : Transform;

 function Update(){
 //the direction vector to target
 var dir = (target.position - transform.position).normalized;
 var hit :RaycastHit;

 if (Physics.Raycast(transform.position,transform.forward,hit ,20)){
    //no self collision 
    if(hit.transform !=transform)
    {
      dir += hit.normal *20;
    }

 }
  var rot = Quaternion.LookRotation(dir);
  transform.rotation =   Quaternion.Slerp(transform.rotation,rot,Time.deltaTime);
  transform.position  += transform.forward *20 *Time.deltaTime;
  
   print (transform.rotation);
   
}