Since GUI Operating Systems emerged, mouse has been the inherent partner. We click, double-click, scroll and do a lot with mouse. No doubt it adds comfort but slows down the productivity. Especially for the programmers who usually work on many windows simultaneously. Be it database console, or coding editor or console, mouse clicks eats up your focus.
tmux is a terminal multiplexer and allows you a single environment. Via this, you can launch multiple windows and switch back and forth. Available on Mac OSX, linux flavours and probably on some UNIX platforms. It seems its port is not available for Windows (Alas!).
On Ubuntu you may install using $sudo apt-get install tmux or you may obtain the source code from http://tmux.sourceforge.net/ and build it.