Just installed IP_Tracker, and there's a couple of small bugs you might like to address.
1. For those of us who have a User table with a different prefix.
index.php line 283 should use $user_prefix for the User table, not $prefix. i.e. the correct line should be:-
$sql = "SELECT i.ipusername, i.ip_address, i.hostname, MAX(date_time), COUNT(*), MIN(ipid), s.uname, u.username FROM ".$prefix."_iptracking AS i LEFT JOIN ".$prefix."_session AS s ON s.uname=i.ipusername LEFT JOIN ".$user_prefix."_users AS u ON u.username=i.ipusername WHERE $filter $modfilter $adminfilter GROUP BY 1,2,3 ORDER BY $orderby $orderdir LIMIT $offset, $numip";
You'll also need to add global $user_prefix; somewhere prior to that line as well.