Buildpkg is a package build system. It gives you the opportunity to create package system (like rpm, dpkg, stc.) independent descriptions (.def) which can be used to create binary packages on every system. It depends on a few commands / utils (see requirements), but it is a shell script. No compilcated installation required. It can be also used to track installations and create packages of the installed files. If you want more safety, you can use the 'jail' feature. In this mode a chroot-ed environment will be created from the (configurable) list of programmes and the installation will be done here. Supported package formats are : slackware's .tgz (incl. doinst script), debian's .deb (incl. postinstall), redhat's .rpm (incl. %post) and the binary only .tar.gz). Besides GNU/Linux, Solaris/SunOS (incl. postinstall) and FreeBSD (incl. postinstall) packages are also supported.
To read more about its features, take a look into the buildpkg.1 man page (at the left side)...