Updated to match the website's slightly changed code, normal use restored.

How to get the right firmware for your iPod/iPhone
Looking to update or restore to another version of your iPod or iPhone, this is the perfect tool. It downloads from an automatically generated list from Apple directly. Select your device/firmware version/firmware build. Hit download, and you're sorted! Enjoy :)

What next?
Once you've downloaded the IPSW file, shift-click (PC) or option-click (Mac) the Restore or Update buttons in iTunes. A file dialog will open and let you choose the downloaded ipsw-file

Is this legal?
Since you're downloading from official apple servers, yes. This is legal

Screenshot

menu * {
  iPod Firmware $chr(9) /iPodFW:ipodfw
}
alias ipodfw { dialog $iif($dialog(ipodfw),-v,-m)) ipodfw ipodfw }
alias ipodfw.getlist { if ($sock(ipodfw)) { sockclose ipodfw } | sockopen ipodfw www.felixbruns.de 80 | did -b ipodfw 3-5 | did -ra ipodfw 6 Downloading iPod firmware list .. | did -r ipodfw 3 | unset %ipodfw.* }
on *:sockopen:ipodfw: {
  sockwrite -nt $sockname GET /iPod/firmware/ HTTP/1.1
  sockwrite -nt $sockname Host: www.felixbruns.de
  sockwrite -nt $sockname $crlf
}
on *:sockread:ipodfw: {
  var %x | sockread %x
  if ($regex(%x,/<option value="(.*)"\s.*>(.*)</option>/Si)) { if ($dialog(ipodfw)) { set $+(%,ipodfw.,$replace($regml(2),$chr(32),_)) $gettok($regml(1),1,34) | did -a ipodfw 3 $regml(2) } }
  elseif (*Copyright* iswm %x) { did -e ipodfw 3-5 | did -r ipodfw 6 | sockclose $sockname }
}
on *:dialog:ipodfw:init:*: { ipodfw.getlist }
on *:dialog:ipodfw:close:*: { unset %ipodfw.* | sockclose ipodfw }
on *:dialog:ipodfw:sclick:*: {
  if ($did == 4) { ipodfw.getlist }
  elseif ($did == 5) {
    if ($did(3)) { 
      if (!$lock(run)) { run %ipodfw. [ $+ [ $replace($did(3),$chr(32),_) ] ] }
      else { noop $input(There is a lock enabled on the "run" command. Here is the link to your download;,ie,Firmware - Link,%ipodfw. [ $+ [ $replace($did(3),$chr(32),_) ] ]) }
    }
    else { noop $input(No firmware selection was made. Please try again,wo,Firmware - Error) }
  }
}
dialog ipodfw {
  size -1 -1 400 140
  title "iPod/iPhone Firmware Files"
  option pixels
  text "How to restore or update your iPod/iPhone:", 1, 5 5 390 15
  text "After downloading the desired firmware below, you can shift-click (PC) or option-click (Mac) the Restore or Update  buttons in iTunes. A file dialog will open and let you choose the downloaded ipsw-file.", 2, 5 25 390 50
  combo 3, 5 85 390 15, drop
  button "Refresh", 4, 190 110 100 23
  button "Download", 5, 295 110 100 23
  text "", 6, 5 115 180 23
}