[devote]

<table id="mytable" border="1">
<tr>
    <td>1</td>
    <td>2</td>
    <td>3</td>
    <td>4</td>
    <td>5</td>
</tr>
<tr>
    <td>6</td>
    <td>7</td>
    <td>8</td>
    <td>9</td>
    <td>10</td>
</tr>
<tr>
    <td>11</td>
    <td>12</td>
    <td>13</td>
    <td>14</td>
    <td>15</td>
</tr>
</table>

<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
<script type="text/javascript">
    $("#mytable td").mouseover(function() {
        var tds = $( this ).parent().find("td"),
            index = $.inArray( this, tds );

        $("#mytable td:nth-child("+( index + 1 )+")").css("background-color", "#f00");
    }).mouseout(function() {
        var tds = $( this ).parent().find("td"),
            index = $.inArray( this, tds );

        $("#mytable td:nth-child("+( index + 1 )+")").css("background-color", "#fff");
    });
</script>