Made this for a guy at MSN, had an idea that others could find this useful too.
Marks user last seens at join event and with !lastseen [nick] you can retrieve the nick's last seen time.
on *:JOIN:#:writeini -n seen.ini seen $nick $ctime
on *:TEXT:*:*:if ($1 = !lastseen) && ($2) { $iif($chan,notice,msg) $nick $iif($chan && $2 ison $chan,$2 is right here.,$iif($readini(seen.ini,seen,$2),Seen $2 before $duration($calc($ctime - $v1),1),Haven't seen $2 around.)) }