http://forumfiles.ru/files/0018/06/05/49628.gif
http://forumfiles.ru/files/0018/06/05/49628.gif
http://forumfiles.ru/files/0018/06/05/22616.gif
http://forumfiles.ru/files/0018/06/05/22616.gif
You can change the button image with your own image
if you have some unique GoDown/GoUp image button creations, please share here

Installation: Administration --> Options --> HTML footer area.
NOTE: Adjust the size  bottom:10px;right:2px; in accordance with the theme that you are using

Simple GoDownGoUp With HTML Code
Code:
<!-- Start  http://bit.ly/forumwanita-->
<a href='#' rel='nofollow' style='display:scroll;position:fixed;bottom:10px;right:2px;' title='Back to Top'><span style='font-size: x-large;'><img src='http://forumfiles.ru/files/0018/06/05/22616.gif'/></span></a><a href='#gotodown' rel='nofollow' style='display:scroll;position:fixed;top:10px;right:2px;' title='Back to down'><span style='font-size: x-large;'> <img src='http://forumfiles.ru/files/0018/06/05/49628.gif'/></a><a name='gotodown'></a>
<!-- End http://bit.ly/forumwanita-->

Installation: Administration --> Options --> HTML footer area.

Very Nice GoDownGoUp with Style
Code:
<!-- Start  http://bit.ly/forumwanita-->
<style>
.go-to-up,.go-to-down {
padding:0;
margin:0px;
display:block;
background-color:transparent;
outline: none 0 transparent;
border:none 0 transparent;
border-radius:10px;
cursor:pointer;
text-align:center; /*alignment*/
opacity: .9; /*transparency*/
width:66px; /*button width*/
height:74px; /*button height*/
}
/*hover arrow*/
.go-to-down:hover,.go-to-up:hover {
opacity:1;
}
#wrp-butt{
overflow:hidden;
position:fixed; /*positioning*/
z-index:9999; /*show on top of all elements on the page*/
right:5px; /*indicates the position, if left */
bottom:10px; /*position from the bottom of the browser window*/
}
</style>
<div id=wrp-butt>
<button class="go-to-up" id="goToTop" onmousedown="$('html,body').animate({scrollTop:0},{ 'duration': 1000, 'easing':'linear' });$(this).css({'margin':'1px -1px -1px 1px'});" onmouseup="$('html,body').stop(true);$(this).css({'margin':'0'})">
<img src="http://forumfiles.ru/files/0018/06/05/22616.gif" alt="go to up" style="vertical-align: middle">
</button>
<button class="go-to-down" id="OnBottom" onmousedown="$('html,body').animate({scrollTop:$(document).height()},{ 'duration': 1000, 'easing':'linear' });$(this).css({'margin':'1px -1px -1px 1px'});" onmouseup="$('html,body').stop(true);$(this).css({'margin':'0'})">
<img src="http://forumfiles.ru/files/0018/06/05/49628.gif" alt="go to down" style="vertical-align: middle">
</button></div>
<!-- End http://bit.ly/forumwanita-->