Fish

fish - the friendly interactive shell.

fish is a smart and user-friendly command line shell for OS X, Linux, and the rest of the family. fish includes features like syntax highlighting, autosuggest-as-you-type, and fancy tab completions that just work, with no configuration required.

Emerge
Install :

To make fish the default login shell, run:

Configuration
fish starts by executing commands in. You can create it if it does not exist. Since the version 2.0 it is possible to configure fish within a webbrowser session.

External resources

 * fish first steps tutorial
 * fish related question on stackoverflow