function colorate($string = '') {
 $color = preg_match('/^[a-z0-9\#]+/i', $string);
 if ($color) {
  echo 'style="background:'.$color;
 } else {
  echo 'style="background:#eee'; // Temel renk.
 }
}
$colors = array('#000000', '#cccccc', '#ff0000', '#ffff00', '#00ff00', '#00ffff'); // Kullanılacak renkler.
//$result = mysql_query("...");
$counter = 0;
while($row = mysql_fetch_array($result)) {
 echo '<div '.colorate($colors[$counter]).'>Content...</div>';
 $counter++;
}
// veya
$count_colors = count($colors);
for ($i = 0; $i <= $count_colors; $i++) {
 echo '<div '.colorate($colors[$i]).'>Content...</div>';
}

//$result = mysql_query("...");
$counter = 0;
while($row = mysql_fetch_array($result)) {
 echo '<div '.colorate($row[renk]).'>Content...</div>';
 $counter++;
}