<?
$dispay_urls = file("randurls.txt");
if(trim($dispay_urls[0])+43200 < time()){
   $urls = file(dirname(__FILE__)."/urls.txt");
   shuffle($urls);
   $fp = fopen(dirname(__FILE__)."/randurls.txt","w+");
   fwrite($fp, time()."\n");
   foreach ($urls as $url)
   fwrite($fp, trim($url)."\n");
   fclose($fp);
   $dispay_urls = $urls;
}else
   array_shift($dispay_urls);

foreach ($dispay_urls as $url) {
    echo "$url";
}
exit;
?>

url_list.txt

$tumb[1]='<a href="url1"><img src="img1" alt="" /></a>';
$tumb[2]='<a href="url2"><img src="img2" alt="" /></a>';
$tumb[3]='<a href="url3"><img src="img3" alt="" /></a>';
$tumb[4]='<a href="url4"><img src="img4" alt="" /></a>';
$tumb[5]='<a href="url5"><img src="img5" alt="" /></a>';
$tumb[6]='<a href="url6"><img src="img6" alt="" /></a>';
$tumb[7]='<a href="url7"><img src="img7" alt="" /></a>';
$tumb[8]='<a href="url8"><img src="img8" alt="" /></a>';
$tumb[9]='<a href="url9"><img src="img9" alt="" /></a>';
$tumb[10]='<a href="url10"><img src="img10" alt="" /></a>';

и сам скриптик, выводит 5 случайных:

<?php
include"url_list.txt";
$kol_url=count($tumb);
for ($i=0; $i<5; $i++) {
$gal=rand(1,$kol_url);
echo"$tumb[$gal]";
    for ($j=$gal; $j<$kol_url; $j++) {
    $tumb[$j]=$tumb[$j+1];
    }
$kol_url--;
}
?>

<?php
$tumb[1]='<a href="url1"><img src="img1" alt="" /></a>';
$tumb[2]='<a href="url2"><img src="img2" alt="" /></a>';
$tumb[3]='<a href="url3"><img src="img3" alt="" /></a>';
$tumb[4]='<a href="url4"><img src="img4" alt="" /></a>';
$tumb[5]='<a href="url5"><img src="img5" alt="" /></a>';
$tumb[6]='<a href="url6"><img src="img6" alt="" /></a>';
$tumb[7]='<a href="url7"><img src="img7" alt="" /></a>';
$tumb[8]='<a href="url8"><img src="img8" alt="" /></a>';
$tumb[9]='<a href="url9"><img src="img9" alt="" /></a>';
$tumb[10]='<a href="url10"><img src="img10" alt="" /></a>';
$kol_url=count($tumb);
for ($i=0; $i<5; $i++) {
$gal=rand(1,$kol_url);
echo $tumb[$gal];
    for ($j=$gal; $j<$kol_url; $j++) {
    $tumb[$j]=$tumb[$j+1];
    }
$kol_url--;
}
?>

<?
$fp2=fopen(dirname(__FILE__)."/urls.txt","r");
$urls = file("urls.txt");
$dat=stat("randurls.txt");
if($dat[10]+43200 < time()){
$fp=fopen(dirname(__FILE__)."/randurls.txt","w+");
$kol_url=count($urls);
for ($i=0; $i<5; $i++)
   {
   $gal=rand(0,$kol_url-1);
   //echo"$urls[$gal]";
   fwrite($fp, trim($urls[$gal])."\n");
   for ($j=$gal; $j<$kol_url; $j++)
    {
    $urls[$j]=$urls[$j+1];
    }
   $kol_url--;
   }
fclose($fp);
}
else{};
$rand_urls = file("randurls.txt");
foreach ($rand_urls as $url)
echo"$url";
?>

<?php

define("SOURCE", "data.txt");
define("OUTPUT", "done.html");
define("COUNT",  3);

if (filemtime(OUTPUT) > time() - 60*60*12) { // 12 hours delay
   $output = file_get_contents(OUTPUT);
} else {
   $data = file(SOURCE);
   shuffle($data);

   $urls = array_slice($data, 0, COUNT);
   $output = implode("\n", $urls);
   file_put_contents(OUTPUT, $output);
}

echo $output;

define("COUNT",  8);