Sometimes you want to use /amsg but it posts the messages only on the current server or you want to set exception for channels.
Well... Here ya go.
The config:

[ymsg]
#planet=0
#help=1

All the channels with a '1' will be ignored on the broadcast, everything else is considered as not filtered.
If you are on 4 channels, two channels in one network, you can type the following command to post a message in all except in the channel #help.

/ymsg Hi guys :D

You can filter channels or add channels for ONCE in the command.
Directly after the command you have to type '+' or '-' for adding, or removing a channel for the broadcast.
Example:

/ymsg +#help.-#vhost.+#yorp Goodbye

With this command the broadcast will be posted in #help, too. It overrides for ONCE the config.
And it removes for ONCE the channel #vhost.

I posted the script and many others earlier on my german blog http://blog.yamahi.eu

    ;--------------------------------------------------- - -  -    -
    ;| YMSG © 06.04.2013
    ;--------------------------------------------------- - -  -    -
    ;| Version: 0.3
    ;| mIRC: v7.32
    ;| Script-Planung: Yama
    ;| Script-Mod: Yama
    ;--------------------------------------------------- - -  -    -
    ;| Beschreibung: Extrem manipulable /amsg
    ;--------------------------------------------------- - -  -    -

    [ymsg]
    #planet=0
    #help=1

    alias ymsg {
      /var %j 1
      /while ( %j <= $scon(0) ) {
        /scon %j
        /var %i 1
        /while ( %i <= $chan(0) ) {
          if ( $left($1,1) == $chr(43) || $left($1,1) == $chr(45) ) {
            /var %m 1
            /while ( %m <= $gettok($1,0,46) ) {
              if ( $left($gettok($1,%m,46),1) == $chr(43) && $right($gettok($1,%m,46),-1) == $chan(%i) )  {
                /msg $right($gettok($1,%m,46),-1) $2-
              }
              /inc %m
            }
          }
          if ( $readini($script,ymsg,$chan(%i)) != 1 ) {
            if ( $chan(%i) !isin $1 ) {
              if ( %m == $null ) {
                /msg $chan(%i) $1-
              }
              else {
                /msg $chan(%i) $2-
              }
            }
          }
          /inc %i
        }
        /inc %j
      }
    }