All 16777215 displayable colors in a webpage.
<?
$fp = fopen("colors.html","w");
fwrite($fp, "<table>");
for ($i=0;$i<=16777215;) {
fwrite($fp, '<tr>');
for ($j=0;$j<=255;) {
fwrite($fp, '<td bgcolor="'.str_pad(dechex($i),6, "0", STR_PAD_LEFT).'"><font color="#FFFFFF">'.str_pad(dechex($i),6, "0", STR_PAD_LEFT).'</font> <font color="#000000">'.str_pad(dechex($i),6, "0", STR_PAD_LEFT).'</font></td>');
  $j++;
  $i++;
}
fwrite($fp, '</tr>');
}
fwrite($fp, "</table>");
?>