Ksh

The Korn Shell, written by David G. Korn at AT&T Bell Labs, the birthplace of Unix. Find it at /bin/ksh, but only after you install it via ports or packages, because it's not part of the base system.

see also: [David Korn's website]

Other shells that you can install and customize for ease of use are the bash, csh, tcsh, psh, ksh, zsh.