BE comes with a number of additional utilities and features that may be useful to power users. We’ll try to keep an up to date list here, but your best bet may be poking around in the source on your own.
misc/completion contains completion scripts for common shells (if we don’t have a completion script for your favorite shell, submit one!). Basic instructions for installing the completion file for a given shell should be given in the completion script comments.
Packagers should install these completion scripts in their system’s usual spot (on Gentoo, the Bash completion script should be installed as /usr/share/bash_completion/be and Z shell completion script should be installed as /usr/share/zsh/site-functions/_be).
Email threads are quite similar to the bugs/issues that BE tracks. There are a number of useful scripts in misc/xml to go back and forth between the two formats using BE’s XML format. The commands should be well documented. Use the usual <command> --help for more details on a given command.