Command lines
JP Software's command lines
4DOS
Available from JP Software, see also JP Software versions. See also: Revived 4DOS, [4DOS.INFO]
TCMD
Freeware 16-bit
Included Caveman technology
Shareware 32-bit
...
4OS/2
Now Freeware. Source available.
Posix command lines
sh (in /bin/)
A file named sh stored in the /bin/ directory of Unix and compatible/clone operating systems has been around since the the first version of Unix. The actual software used has varied: Originally it was the Thompson shell, and later it was the PWB Shell, a.k.a. the Mashey shell, maintained in part by John Mashey. Later on the file would often refer to either the Bourne shell or the C shell. In modern day systems, it is often simply a copy of another shell, bash or ksh, which dumbs itself down to act like an older shell when its filename is called /bin/sh. The most notable feature of present day /bin/sh is a degree of compatibility: Scripts cound on /bin/sh to exist and to operate in certain ways. For actual interactive use, a different shell is generally recommended.
Public Domain Korn shell, or OpenBSD's ksh

With an executable filename of ksh in /bin, this has also be abbreviated as pdksh or oksh.

OpenBSD's FAQ 10 (ksh section) cites this being the same executable as sh. It appears to be a bit simpler of software than bash, but still supporting key popular features such as tab completion, command line editing, and so forth. OpenBSD's implementation is based on pdksh which has only for pdksh's simple licensing requirements.

A port called oksh: OpenBSDs ksh for Linux has been made, adding the restrictions of GPLv3. A Debian package (which unsurprisingly works on something called Debian, and also Ubuntu) has been made for Debian Etch. The web site gives an example of setting PS1: Apparently running:
export PS1='\u@\h#'
to get a prompt showing the username and hostname followed by a pound sign, isn't something all ksh implementations can use.

Bourne-again shell (bash)
If ksh isn't available but one wants a shell with command line features like tab completion and some nicer command line editing, then bash may be available. It is installed by default on Ubuntu. OpenBSD FAQ 10: ksh section references bash but it isn't built into the operating system, probably due to being overly complex software compared to alternatives (making it more difficult to fully audit logic for security), or due to licensing issues, or due to increased size combined with unnecessity.
C Shell (csh)

Another alternative, used in 2BSD in 1979 to replace the Bourne shell.

Instead of using sh's syntax:
VARNAME=newval
export VARNAME
 (or perhaps “ export VARNAME=newval “) in csh, the commonly used syntax is:
“ setenv VARNAME=newval ” (referencing ftp://ftp.netbsd.org/pub/NetBSD/NetBSD-4.0/i386/INSTALL.html for comparison)

There is also tcsh ( Tenex-csh according to NetBSD 4.0 i386 INSTALL.html )

Bourne shell
This may be named /bin/sh.
Command line history
For DOS

DOSKey comparison chart compares DOSKey to 4DOS and a regular prompt. DOSKey supports command line history, and keyboard aliases. So does 4DOS.

There are some freeware/shareware products that also perform such a thing.

For Posix
Built into the popular shells.
Graphical Shells
Windows 3.1 had one or more alternate shells. Text
Text mode modifiers
See the command line programs section of this page. Also:
Scrollback buffer
For DOS
Peruse. Also, the Confix.Sys driver may be useful to stop the screen early on. For Peruse, see v13n07.zip
For Posix
The program screen supports scrollback (by pressing Control A, and then up arrow). Other things one can try are PageUp, Shift-PageUp, and/or Control-PageUp. If one or more of those work, keep in mind that changing terminal windows (Alt-Fkey, or is it Alt-Ctrl-Fkey?) may cause the video buffer to lose track of what is stored, eliminating the possibility to scroll back (as much). If one wishes to view the initial boot screen, a program called dmesg may be available.
Text mode resolution setter
tm103 (Jason Hood), ROW.EXE (Command line, config.sys, for DOS and OS/2 family mode), Confix.Sys
Mouse copy/paste
For DOS
...
For Posix
For OpenBSD
wmouse? wsmouse?
Others
moused? vmouse/vmoused? Others?
Interface options/setters
MS TweakUI, More Control. Also, programs that allow options to change are often classified as drivers. For example:
Boot-up modifiers
See Pre-Boot software for boot menus. Also:
Modifying boot parameters
For DOS
Some versions of DOS have boot menus. (Can Confix.Sys help with this?) There are shareware alternatives. There is a shareware program that runs commands.
Posix
Loadlin
Command line, graphical version
Boot command (for OpenBSD)
See the boot config program info in OpenBSD FAQ.