This is a modified version of some script I found elsewhere on the web. I don't even have the original script anymore actually....

It gives random colors to nicknames when they first speak in a channel. It skips the black color (since I am using a black background). If you'd like to skip another color you can change that "0" on line 11 to be 1 less than the color code you want to skip.

I should make this read the background color from the configuration actually and skip it on it's own.

on *:START:{
  var -g %currentcolor 2
}

on ^*:text:*:#:{
  if ($cnick($nick).color == $color(normal text)) { 
    .cnick $nick %currentcolor
    if (%currentcolor == 15) { 
      set %currentcolor 0
    }
    elseif (%currentcolor == 0) { 
      set %currentcolor 2
    }
    else {
      inc %currentcolor
    }
  }
}