There are a number of ways to do this. The easiest is to create a new div within your includes/templates/YOUR_TEMPLATE/common/tpl_main_page.php, with something like:

Code:
<div id="bottomRight"><ahref="#"><img="link to image" alt="Crafty" /></a></div>
Then add the follwing code to the bottom of your stylesheet:

Code:
#bottomRight {
position: absolute;
right:0px;
left:0px;
}
That should do it. Just make sure teh div you add is the very last thing before the </body> tag, otehrwise it may position absolutely within another object.

Absolute