Install the URxvt and weechat plugins and have desktop-notifications from weechat even over SSH and from inside TMUX.
The format of notification messages is as follows:
$ printf "\e]777;im-notify;%d;%d;%s\a" 0 0 nick
If the first argument is
1, no notification sound is played. If the second
1, no notification sound is played '''and''' no notification is