I have been using Unix systems for over 20 years: I can’t believe I missed the Unix screen utility for using multiple screens in a shell window. (I was browsing the web late last night on my new N800 web pad, and saw a post on Digg about screen – I tried it first thing this morning when I turned on my laptop.)
Here is a short introduction to its use but all you really need to know to get started is to run the program, use control-a c to create new views, control-a a to send a control-a to a running program (useful for emacs and use control-a n and control-a p to cycle through “next” and “previous screens.
Screen comes pre-installed on OS X and is an easy install on Linux if your distro does not already include it. If you love the command line, screen is definitely worth a few minutes of experimentation to see how you like it.