This is ratmenu, a simple program that allows you to create X menus from the shell. Although designed for ratpoison, it will work with any ICCCM compliant window manager.

It was forked from 9menu version 1.5, to provide specific support for the ratpoison window manager. Where 9menu only responds to the mouse, and ignores the keyboard, ratmenu has all mouse sensitivity taken out, and only responds to the keyboard. Since then it has evolved nifty features and behaviors of its own. The source code was also cleaned up and old cruft weeded out.