Emacs 23 adds support for daemon mode (via "emacs --daemon"), which is like Emacs Server in that you can connect to it and open files using emacsclient, except that you do not have to have any frame open. I use the following shell aliases to send files to the daemon, run Emacs commands, and open new frames:
# start a windowed frameI also set EDITOR so that most programs use the daemon to open files:
alias ec="emacsclient -n -c -a emacs"
# start a terminal frame
alias em="emacsclient -t -a emacs -nw"
# do not start a new frame
alias ea="emacsclient -n -a emacs"
export EDITOR="emacsclient -t"I use daemon mode like GNU Screen, though I also leave Emacs terminal frames open inside Screen windows.