<table id='music'>
<tr id='1'><td>1</td></tr>
<tr id='2'><td>2</td></tr>
<tr id='3'><td>3</td></tr>
<tr id='4'><td>4</td></tr>
<tr id='5'><td>5</td></tr>
<tr id='6'><td>6</td></tr>
<tr id='7'><td>7</td></tr>
</table>
<script>
var table=document.getElementById('music'), tr=table.getElementsByTagName('tr'), i=tr.length;
table=tr[0].parentNode; //ибо tbody итп
while(i--) Math.random()<.5 ? table.appendChild(tr[i]) : table.insertBefore( tr[i], table.firstChild );
</script>