BusyBox

Busybox is a program with small memory footprint, designed to replace a suite of otherwise large Linux utilities. It is commonly used in embedded Linux systems. Over 58 projects are listed on the busybox projects page.

The text segment is only loaded once. Subsequent calls to subprograms use the same text segment, saving memory.

Additionally, it is highly configurable. Only the required applets are compiled in reducing storage requirements.

See http://www.busybox.net/

A good article on busybox is at: http://www-128.ibm.com/developerworks/linux/library/l-busybox/