I hang out on several separate networks, and on several channels on each network, and in the end, this results in more than 19 windows within irssi. (I use irssi within tmux, if it matters.) ...
I use Mac OS X and Arch Linux and occasionally log into FreeBSD and Debian servers by ssh. My favoured tools are zsh, ssh, tmux, git, vim and irssi. I use iTerm2 on Mac OS X and unicode-rxvt on Arch ...