Old Unix tools, ready-to-compile for modern Unix systems

Today I stumbled across The Heirloom Toolchest, a collection of standard Unix utilities, taken from all the ancient Unix source code published by Caldera a few years ago. They're packaged ready-to-compile, and quite small, yet providing all the functionality you usually need. This package is definitely a good thing, as it provides a good base for building a small system based on diet libc.