Mine

on *:text:!greets*:#:{ if ($nick isop $chan) {
    if ($2 == on)set $($+(%Greets.,$chan)) on | notice $nick Greets are now On for this channel.
    if ($2 == off) unset $($+(%Greets.,$chan)) | notice $nick Greets are now Off for this channel.
    else { notice $nick You must be an Op in this channel.
    }
  }
}