position	Rectangle on the screen to use for the scrollbar.
value	The position between min and max.
size	How much can we see?
topValue	The value at the top of the scrollbar.
bottomValue	The value at the bottom of the scrollbar.
style	The style to use for the scrollbar background. If left out, the horizontalScrollbar style from the current GUISkin is used.

Returns
float The modified value. This can be changed by the user by dragging the scrollbar, or clicking the arrows at the end.

Make a vertical scrollbar. Scrollbars are what you use to scroll through a document. Most likely, you want to use scrollViews instead.

	var vSbarValue : float;
	function OnGUI () {
		vSbarValue = GUI.VerticalScrollbar(Rect (25, 25, 100, 30), vSbarValue, 1.0, 10.0, 0.0);
	}

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    public float vSbarValue;
    void OnGUI() {
        vSbarValue = GUI.VerticalScrollbar(new Rect(25, 25, 100, 30), vSbarValue, 1.0F, 10.0F, 0.0F);
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	public vSbarValue as float

	def OnGUI() as void:
		vSbarValue = GUI.VerticalScrollbar(Rect(25, 25, 100, 30), vSbarValue, 1.0F, 10.0F, 0.0F)

Finding extra elements:

The styles of the buttons at the end of the scrollbar are searched for in the current skin by adding "upbutton" and "downbutton" to the style name. The name of the scrollbar thumb (the thing you drag) is found by appending "thumb" to the style name.

	var scrollPos : float = 0.5;
	// This will use the following style names to determine the size / placement of the buttons
	// MyVertScrollbarupbutton    - Name of style used for the up button.
	// MyVertScrollbardownbutton - Name of style used for the down button.
	// MyVertScrollbarthumb         - Name of style used for the draggable thumb.
	function OnGUI() {
		scrollPos = GUI.VerticalScrollbar(Rect(0,0,100,20), scrollPos, 1, 0, 100, "Scroll");
	}