One thing that I've been wanting is to get Growl notifications from irssi, which I'm running on a remote server, as I do when using, e.g., Colloquy. By googling a little I found this great write up on how to enable growl notifications. 

First you need to get the 'fnotify.pl' script from here which writes to a file every time anyone is messaging you or anything that you have chosen to /hlight, We also need 'growlnotify' which is in Growl's dmg extras folder.

1. Put growlnotify in your path. I use my ~/bin folder.
2. Copy the 'fnotify.pl' to the remote server's ~/.irssi/scripts folder (make a scripts folder if it does not exists)
3. Finally, put this script below into your path. I use my ~/bin folder. It connects to the remote server and tails the pnotify file which is then piped back to the client which does the notification using growlnotify.

#!/bin/bash
 (ssh myuser@irssi-remote-server -o PermitLocalCommand=no  \
     ": > .irssi/fnotify ; tail -f .irssi/fnotify " | \
   while read heading message; do                    \
     growlnotify -t "${heading}" -m "${message}";     \
   done)& 

There is one hitch though, if the connection to the server is closed the command does not exit. So the next time I logon I'll have two processes runnning...