PHP Code:
$standings=mysql_query("select * from user ORDER BY rating DESC LIMIT 8");
while($rows=mysql_fetch_array($standings))
{
$player=$rows['username'];
$rating=$rows["rating"];
$id=$rows['userid'];
$standingbit .= "<tr><td><a href=http://www.starcraftdream.com/forums/member.php?u=$id>$player</a></td><td>$rating</td></tr>";
}
I have no idea about the other structure of your page so I'm guessing you echo $standbit somewhere else. Anyways the code above should work

You forgot the concatenation operator

(.=)