Simple - but complete enough - command-line Bash debugger, written as a Bash script. No installation and no root permission required: just download, put every where you prefer and use it.
Bash 3 required.
uniread - universal readline - adds full readline support (command editing, history, etc.) to any existing interactive command-line program. Common examples are Oracle's sqlplus or jython.
uniread will work on any POSIX platform with Perl.