i made this script out of other pieces, and gived it a touch of myself...

this is a joins window for mirc
it registers users who get online and put them in a window
if it runs for over a week or soo, you'll start to see more and more info,

preview:
[12:20] LadyTjuh !jeugd@CW-2432DFCD.chello.nl has joined #Chatfun
[12:20] LadyTjuh joined #Chatfun 9 times, last: 1day 2hrs 8mins 34secs ago
[12:20] LadyTjuh`s previous nicks: sweet_girly, Sweety-girl, cool-girly, Cool-lady, chat-girly, LadyTjuh
[12:20] * comchans with LadyTjuh: #Chatfun.

it also shows clones if any...

i know the script is messy, but im not into organised coding
if you want to steal, grab, copy it, i dont care.. as long as it brings you fun

im not planning to update this,

screenshot:

on *:LOAD: {
  ; since this script is not designed for multi-server use, this is neccesary
  set %joins.network $$?="Please enter the name of the network you want this script to work for..."
}

on *:start: {
  nicktracker
  window -Sikzl15 @joins
  window -ikz @whois
  ;clean the joinswindow every hour
  .timerclean 0 3600 /clean_joins
  ;update (fill) the joinswindow every 10 seconds
  ;PLEASE NOTE THAT THIS IS SET TO SCON 1 
  ;CHANGE THIS IF YOU WANT TO USE ANOTHER SERVER CONNECTION
  .timerupdate 0 10 .scon 1 /update_joins
  if (!%joins.network) { set %joins.network $$?="Please enter the name of the network you want this script to work for..." }
}

on *:QUIT: {
  if ($fline(@joins,$nick,1,1)) { /dline -l @joins $fline(@joins,$nick,1,1) }
}

on *:PART:#: {
  if ($fline(@joins,$nick,1,1)) { /dline -l @joins $fline(@joins,$nick,1,1) }
}

on *:TEXT:*:#: {
  .joins_user
  if ($network != %joins.network) { halt }
  if ($fline(@joins,$nick,1,1)) { halt }
  aline -l @joins $nick
}

on *:KICK:#: {
  if ($fline(@joins,$knick,1,1)) { /dline -l @joins $fline(@joins,$knick,1,1) }
}

on *:nick: {
  if ($fline(@joins,$nick,1,1)) { /rline -l @joins $fline(@joins,$nick,1,1) $newnick }
  else { if ($network == %joins.network) { aline -l @joins $newnick } }
  if (!$hget(join)) nicktracker
  var %a = 1,%n = 0
  while $hget(join,$address($newnick,2) $+ .nicknum. $+ %a) {
    if ($v1 == $newnick) %n = 1 
    inc %a
  }
  if (%n == 0) hadd join $address($newnick,2) $+ .nicknum. $+ %a $newnick

}

on ^*:join:#: {
  if ($nick == $me) { halt }
  if (!$fline(@joins,$nick,1,1)) { if ($network == %joins.network) { aline -l @joins $nick } }
  if (!$hget(join)) nicktracker
  hinc join $address($nick,2) $+ $chan $+ .num

  ; fill the messages in @joins window
  if ($hget(join,$address($nick,2) $+ $chan $+ .last)) echo # 03 $+ $timestamp * $nick 01 $+ $address($nick,2) 03has joined # - Joined $hget(join,$address($nick,2) $+ $chan $+ .num) times - Last as $hget(join,$address($nick,2) $+ $chan) $duration($calc($ctime - $hget(join,$address($nick,2) $+ $chan $+ .last))) ago
  else echo # 03 $+ $timestamp * $nick 01 $+ $address($nick,2) 03has joined # - First join
  aline @joins 03 $+ $timestamp * $nick 01 $+ $address($nick,0) 03has joined #
  if ($hget(join,$address($nick,2) $+ $chan $+ .last)) { aline @joins 03 $+ $timestamp * $nick joined # 01 $+ $hget(join,$address($nick,2) $+ $chan $+ .num) 03times, last:01 $duration($calc($ctime - $hget(join,$address($nick,2) $+ $chan $+ .last))) 03ago }
  else { aline @joins 03 $+ $timestamp * $nick never joined # before }

  ; add new data to database
  hadd join $address($nick,2) $+ $chan $nick
  hadd join $address($nick,2) $+ $chan $+ .last $ctime
  var %a = 1,%n = 0,%b = 1
  while $hget(join,$address($nick,2) $+ .nicknum. $+ %a) {
    if ($v1 == $nick) %n = 1 
    inc %a
  }
  if (%n == 0) hadd join $address($nick,2) $+ .nicknum. $+ %a $nick

  ;output some more data
  aline -p @joins 03 $+ $timestamp * $nick $+ `s previous nicks:01 $checknick($nick)
  if ($file($logdir $+ $nick $+ . $+ $network $+ .log)) { aline @joins 03 $+ $timestamp * You have Query logs from01 $nick }
  aline -p @joins 03 $+ $timestamp * comchans with $nick $+ : 01 $+ $comchans($nick) $+ .

  ; clonescanner
  while $nick(#,%b) {
    if ($nick(#,%b) != $nick) && ($address($nick(#,%b),2) == $address($nick,2)) aline @joins 4 $+ $timestamp * $nick(#,%b) is a clone from $nick $+ !
    inc %b
  }

  ; add an empty line and halt other defaults
  aline @joins 
  haltdef
}

;tracks nicks
alias nicktracker {
  hmake join 1000
  hload join join.hsh
  .timer 0 600 hsave join join.hsh
}

;search previous nicks
alias prevnicks {
  if (!$hget(join)) nicktracker
  var %a = 1,%s
  while $hget(join,$address($1,2) $+ .nicknum. $+ %a) {
    %s = %s $v1
    inc %a
  }
  echo -a -->12 $1 has had the nicks:4 %s
}

;search common chans with an user
alias comchans {
  /var %x 0
  :comchanloop
  /inc %x
  if ($1 ison $chan(%x)) {
    if (!%y) { /var %y $chan(%x) }
    else { /var %y $+(%y,$chr(44),$chr(32),$chan(%x)) }
  }
  if (%x < $chan(0)) {
    goto comchanloop
  }
  /return %y
}

;update the current online users (topic)
alias joins_user {
  renwin @joins @joins $line(@joins,0,1) users online
}

;check old nicknames on hostmask
alias checknick {
  if ($1 isin $read(nicks.txt, s, $address($1, 2))) { 
    return $read(nicks.txt, s, $address($1, 2)) 
    halt 
  }
  if (($read(nicks.txt, w, $address($1, 2) $+ *)) && ($1 !isin $read(nicks.txt, s, $address($1, 2)))) { 
    var %oldnicks $read(nicks.txt, s, $address($1, 2))
    /write -s $address($1, 2) nicks.txt $address($1, 2) %oldnicks $+ , $1
    return $read(nicks.txt, s, $address($1, 2)) 
    halt
  }
  /write nicks.txt $address($1, 2) $1
  return $read(nicks.txt, s, $address($1, 2)) 

}

;fill the sidebar with online users
alias update_joins {
  set %z $chan(0)
  while (%z >= 1) {
    set %y $nick($chan(%z),0)
    while (%y >= 1) {
      aline -nl @joins $nick($chan(%z),%y)
      dec %y
    }
    dec %z
  }
}

;repeat info (+ some whois info)
alias getinfo {
  whois $1
  .enable #getinfo
  aline @joins 03 $+ $timestamp * $1 $+ 's host is01 $address($1, 5)
  aline -p @joins 03 $+ $timestamp * $1 comchans: 01 $+ $comchans($1)
  aline -p @joins 03 $+ $timestamp * $1 $+ 's other nicknames:01 $checknick($1)
  set %x $numtok($comchans($1), 44)
  while (%x >= 1) {
    aline @joins 03 $+ $timestamp * $1 joined01 $gettok($comchans($1), %x, 44) 04 $+ $hget(join,$address($1,2) $+ $strip($gettok($comchans($1), %x, 44)) $+ .num) 03times, last:01 $duration($calc($ctime - $hget(join,$address($1,2) $+ $strip($gettok($comchans($1), %x, 44)) $+ .last))) 03ago

    dec %x
  }
  .timerget2 1 1 .disable #getinfo
  .timerget 1 1 aline @joins 

}

;checks users that are in the list, but are not online
alias clean_joins {
  set %x $line(@joins,0,1)
  while (%x >= 1) {
    if (!$address($line(@joins,%x,1),2)) { /dline -l @joins %x }
    dec %x
  }
}

#getinfo off
;whois information for getinfo
raw *:*: { 
  if ($istok($whoisnumerics,$numeric,124)) haltdef
  if ($numeric == 301) aline @joins 11? Away: Yes: ( $+ $3- $+ ) 
  elseif ($numeric == 307) aline @joins 03 $+ $timestamp * Registered Nickname: 01Yes.
  elseif ($numeric == 310) aline @joins 03 $+ $timestamp * IRC Helper: 01Yes.  
  elseif ($numeric == 311) {
    aline @joins 03 $+ $timestamp * Real Name:01 $6- 
  }
  elseif ($numeric == 312) aline @joins 03 $+ $timestamp * Server:01 $3 
  elseif ($numeric == 313) aline @joins 03 $+ $timestamp * Network Functions:01 $5-9

  elseif ($numeric == 317) {
    aline @joins 03 $+ $timestamp * Signed on at:01 $asctime($4,dddd dd/mm/yyyy HH:nn:ss) 
    aline @joins 03 $+ $timestamp * Time idle:01 $duration($3) 
    aline @joins 03 $+ $timestamp * Time online:01 $duration($calc($ctime - $4)) 
  }
  elseif ($numeric == 320) aline @joins 03 $+ $timestamp * Swhois:01 $2- 
  elseif ($numeric == 330) aline @joins 03 $+ $timestamp * Authname:01 $3 
  elseif ($numeric == 335) aline @joins 03 $+ $timestamp * Bot:01 Yes
  elseif ($numeric == 338) {
    aline @joins 03 $+ $timestamp * Real Hostmask:01 $3 
    aline @joins 03 $+ $timestamp * Real IP:01 $4 
  }
  elseif ($numeric == 378) aline @joins 03 $+ $timestamp * Connecting from:01 $6-  
  elseif ($numeric == 379) aline @joins 03 $+ $timestamp * Modes:01 $6-
  elseif ($numeric == 671) aline @joins 03 $+ $timestamp * Secure Connection:01 Yes
}
#getinfo end

;menu for joinswindow
menu @joins {
  clear window:/clear @joins
  clear listbox:/clear -l @joins
  clean listbox:/clean_joins
  $iif($$1, get info):/getinfo $$1
  $iif($$1, del user):/dline -l @joins $fline(@joins,$$1,1,1)
}

;menu for checking an users previous nicks in a channel
menu nicklist {
  Previous nicks:/prevnicks $$1
}