This script is similar to Lindrian's snippet for /findip, but I completely rewrote it my own way and with different features.

What it does: You can add/delete a nick and their IP in an ini file, then type !getip to search the ini. (This is for when a person is offline) Or, you can type !findip to search anyone on IRC at the time.

Also, you can type !getnick to find a nick used for an IP.

To find the nick a saved user's IP is using, type !getnickip.

Examples:

!addip/!delip sharpknife - Adds/deletes sharp|knife from ips.ini

!getip sharpknife - Searches ips.ini for sharpknife's IP

!findip sharpknife - Searches your IRC server for sharpknife's IP

!getnick Swift-65B870F1.sip.rdu.bellsouth.net - Searches your IRC server for a user with that address

!getnickip sharpknife - Searches ips.ini for sharpknife's IP, then uses that to find the nick sharpknife is on.

on *:TEXT:!addip *:#:{ 
  if ($address($nick,2)) == (your address here) { 
    writeini ips.ini $2 IP $3-
    notice $nick IP for $2 added.
  }
}

on *:TEXT:!delip *:#:{ 
  if ($address($nick,2)) == (your address here) { 
    remini ips.ini $2
    notice $nick IP for $2 deleted.
  }
}

on *:TEXT:!getip *:#:{
  if ($address($nick,2)) == (your address here) {
    notice $nick $2- $+ 's IP is: $readini(ips.ini,$2,IP)
  }
}

on *:TEXT:@getip *:#:{
  if ($address($nick,2)) == (your address here) {
    msg $chan $2- $+ 's IP is: $readini(ips.ini,$2,IP)
  }
}

on *:TEXT:!findip *:#:{ 
  if ($address($nick,2)) == (your address here) {
    notice $nick $2- $+ 's IP is: $ial($2).host
  }
}

on *:TEXT:@findip *:#:{ 
  if ($address($nick,2)) == (your address here) {
    msg $chan $2- $+ 's IP is: $ial($2).host
  }
}

on *:TEXT:!getnick *:#:{
  if ($address($nick,2)) == (your address here) {
    notice $nick Nick associated with $2 is: $ial($2).nick
  }
}

on *:TEXT:@getnick *:#:{
  if ($address($nick,2)) == (your address here) {
    msg $chan Nick associated with $2 is: $ial($2).nick
  }
}

on *:TEXT:!getnickip*:#:{
  if ($address($nick,2)) == (your address here) {
    notice $nick Nick being used by $readini(ips.ini,$2,IP) $+ : $ial(*!*@ $+ $readini(ips.ini,$2,IP)).nick
  }
}

on *:TEXT:@getnickip*:#:{
  if ($address($nick,2)) == (your address here) {
    msg $chan Nick being used by $readini(ips.ini,$2,IP) $+ : $ial(*!*@ $+ $readini(ips.ini,$2,IP)).nick
  }
}