может так?
<body>
<table id="blocks_table">
<tr>
<td><img class="menu_block" alt="Камень" src="http://javascript.ru/forum/images/smilies/laugh.gif"></td>
<td><img class="menu_block" alt="Земля" src="http://javascript.ru/forum/images/smilies/smile.gif"></td>
<td><a href="#"></a></td>
</tr>
</table>
<div id="element" style="border: 1px solid black; width: 20px; height: 20px"></element>
<script>
tmp="http://javascript.ru/forum/images/smilies/angry.gif"
element.onclick=function(){element.style.backgroundImage="url("+tmp+")"}
paste=function(){tmp=this.src}
;[].forEach.call(document.querySelectorAll(".menu_block"), function(block){
block.onclick=paste
})
</script>
</body>