mk-configure is a lightweight replacement for GNU autotools written in and for bmake (a portable version of NetBSD make). The main goal is to have only one top-level tool instead of aclocal+automake+autoconf+autoheader. Other goals are clean design, simplicity, and "no code generation".
Spack is a standalone package manager with its own CPIO-based package format but aiming to keep total compatibility with Slackware Linux. Written in POSIX shell as much as it makes sense, it attempts to provide a fairly complete toolkit to build, install, remove, list, retrieve, and arrange your packages. It can be used as an alternative to Slackware's pkgtools, just to independently and properly manage your local software on any distribution, or as the main package manager of the distribution you build yourself.