neat

<?php
require("includes/conn.php");

if (isset($_GET["imagecount"]))
$next = (int)$_GET["imagecount"]; //int is for sql injection
else
    $next = 0;
    $result = mysql_query("select * from people WHERE id=$next") or die ("haznot DB: " . mysql_error());
    while ($row = mysql_fetch_assoc($result))
    {
       echo "<img src=\"images/" . $row['filename'] . "\" alt=\"\" /><br />";
    }
?>
<!-- this next line will not work if you are missing an number. For example your id is 7, 8 has been deleted, so 9 would be next -->
<a href="images.php?imagecount=<?php echo $next+1; ?>">Next</a>