Something

<script type="text/javascript">
function checkall(formname,thestate){
var el_collection=eval("document.forms."+formname)
for (c=0;c<el_collection.length;c++)
{
if(el_collection[c].type=='checkbox') el_collection[c].checked=thestate;
}
 
}
</script>
<div align="right">
<a href="javascript:checkall('action','true')">Seleccionar todas</a>
<a href="javascript:checkall('action','false')">Seleccionar nenhuma</a>
</div>