Cita: <table width="100%" border="0">
<tr onclick='marcame(this)'>
<td>HOLA</td>
<td>CHAO</td>
</tr>
<tr onclick='marcame(this)'>
<td>LINDO</td>
<td>FEO</td>
</tr>
<tr onclick='marcame(this)'>
<td>FACIL</td>
<td>DIFICIL</td>
</tr>
</table>
Cita: <script language="javascript">
function marcame(campo)
{
campo.style.backgroundColor = "#0000FF";
}
</script>
Espero que esto te sirva..
Salud!!