IPython
Command shell for interactive computing in multiple languages
...Extensible tab completion, with support by default for completion of python variables and keywords, filenames and function keywords. Extensible system of ‘magic’ commands for controlling the environment and performing many tasks related to IPython or the operating system. A rich configuration system with easy switching between different setups (simpler than changing $PYTHONSTARTUP environment variables every time). Session logging and reloading. Extensible syntax processing for special purpose situations. Access to the system shell with user-extensible alias system. Easily embeddable in other Python programs and GUIs. ...