Fink is a package management system for Mac OS X and Darwin systems. It utilizes Debians apt and dpkg tools, while "fink" itself is the source to package building system. The project also adapts sources for broader compatibility with Mac/Darwin systems.
deb-pkg-tools is a Python module for managing Debian packages. It provides for inspecting, building, checking and signing packages, or managing repositories. deb-pkg-tools thereby bases its API on manual meta data parsing or wrapping calls to native tools, such as dpkg, dpkg-deb, lintian, apt-get, apt-ftparchiv, gzip, fakeroot, gpg, dpkg-scanpackages.
wpkg.exe is a package manager for Windows, which is fully compatible with the Debian package format, and also implements APT-style dependency resolution. It also runs on Linux and MacOSX, and there's a graphical frontend alternatively. It supports package installation with implicit repositories over various protocols.
Alien is a Linux software package conversion tool. It transforms between Debian (.deb), Red Had (.rpm), Solaris (.pkg) and Slackware (.tgz/txz) archives. After transforming meta data and contained installation scripts, it can even install them right away. It runs most robustly on Debian-based systems, but also works with less frequently used RPM distros.
Debreate is a tool that helps building Debian packages (.deb). It provides an easy to use interface to set control and meta information, select files for packaging, dependencies, and add scripts.