Fish shell is a modern command shell that offers great features. One of my favorite is that fish will parse man pages and provide command hints as you type a command. More about fish shell can be found at

Fish shell can be easily install on Ubuntu with the following commands.

sudo apt-add-repository ppa:fish-shell/release-2
sudo apt-get update
sudo apt-get install fish

This command makes fish the default shell.

chsh -s /usr/bin/fish