Zsh

zsh or The Z Shell is one of the newest shells with an enhanced command line editing interface.

RedHat's
Find zsh-*.rpm in your distribution or simply search via RPM Search and download the file. run as root  

Debian
zsh can be installed from Debian's main repository, using your APT front end of choice. For example, run as root:   or   will install zsh and any packages on which zsh depends. A package with documentation, zsh-doc is also available.

Gentoo
Currently avalible 4.2.6 stable version. If you want to install zsh on gentoo, simply type in console:  

FreeBSD
 

Unicode support.
At this time the developent versions of zsh support utf-8 (your can simply install zsh from cvs. With this feature you can use zsh with any language.

Default Shell
To setup zsh for day-to-day use, it's posible to change default shell (don't use the feature with root user if you don't understand this).  

Features
The Zshell(Zsh) has comfortable history. You can also tune history engine in zsh.