vitek25,
Вариант...сохранять данные предыдущего нажатия
<!DOCTYPE HTML>
<html>
<head>
<style type="text/css">
tr.tab_act td{
background: #FFFF33
}
</style>
<title></title>
</head>
<body>
<table width="300" height="100" border="1">
<tr onclick="shHide(this)" >
<td></td>
<td></td>
<td></td>
</tr>
<tr onclick="shHide(this)">
<td></td>
<td></td>
<td></td>
</tr>
<tr onclick="shHide(this)">
<td></td>
<td></td>
<td></td>
</tr>
<tr onclick="shHide(this)">
<td></td>
<td></td>
<td></td>
</tr>
</table>
<script type="text/javascript">
shHide = function (c) {
var a;
return function (b) {
a != b ? (b.className = c, a && (a.className = ""), a = b) : a = b.className = ""
}
}("tab_act");
</script>
</body>
</html>