Grab and Drag Camera Style

Does anyone know of a tutorial that will help me make a grab and drag style camera? I want to be able to click and drag on the surface of the game world to move the camera around on the x-y axis (not up and down). I have written this script for the camera and it works, but it's really half assed since i don't really know how to make exactly what i want.

P.S. The reason I am changing Y to Z is because Input.mousePosition returns Y as up and down and for some stupid reason transform.position uses Z as up and down. Why can't everything just use Z?

Code (csharp):

1.  
2. var HasClicked = false;
3. var ClickedPosition = Vector3(0,0,0);
4.  
5. function Start ()
6. {
7.    
8. }
9.  
10. function Update ()
11. {
12.     if (Input.GetMouseButton(0))
13.     {
14.         if (HasClicked == false)
15.         {
16.             ClickedPosition = Input.mousePosition;
17.             HasClicked = true;
18.         }
19.  
20.         var NewVec = ClickedPosition - Input.mousePosition;
21.         NewVec.z = NewVec.y;
22.         NewVec.y = 20;
23.  
24.         transform.position = NewVec;
25.     }
26.     else
27.     {
28.         HasClicked = false;
29.     }
30. }

Thanks

 

I came accross a script that included some 3ds max like controls which included panning plus others. I have just done a quick search for it now but it's somewhere I can't remember so in the meantime you may find something on this page useful to your question.

http://answers.unity3d.com/questions/26079/left-click-and-pan.html

EDIT: You should be able to find it here http://wiki.unity3d.com/index.php/MouseOrbitZoom

This is the bit I was talking about

Code (csharp):

1.  
2. // otherwise if middle mouse is selected, we pan by way of transforming the target in screenspace
3. else if (Input.GetMouseButton(2))
4. {
5.     //grab the rotation of the camera so we can move in a psuedo local XY space
6.     target.rotation = transform.rotation;
7.     target.Translate(Vector3.right * -Input.GetAxis("Mouse X") * panSpeed);
8.     target.Translate(transform.up * -Input.GetAxis("Mouse Y") * panSpeed, Space.World);
9. }
10.