This sounded like fun, so I had a go at implementing it for bash using ANSI control codes[0][1] (though other people have posted much better solutions). You still have to look at the bottom to see the command's output though, so I'm not sure you gain much. If you're having neck troubles, is adjusting your monitor an option?

[0] http://pastebin.com/xaLFyXtT - implementation

[1] http://www.termsys.demon.co.uk/vtansi.htm - reference for some ANSI control codes