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.
Package Changes Analyzer (pkgdiff) can compare and show differences between Linux software packages. It supports reading from RPM, DEB, TAR.GZ and other common formats. It's intended for maintainers to test compatibility and consistency between archive versions.
FPM is an incomplex software package build tool. It can import distribution files simply from source directories or zips, and generate RPM, DEB, TAR.GZ, Solaris packages, or OSXpkg from there. It also provides unified command line options for defining dependencies or add common meta attributes.
XPM is an experimental branch of fpm (effing package management). Both simplify generating DEB, RPM, OSX, Solaris packages and some language-specific bundle systems. Cross package maker (XPM) adds simpler target building per "-t deb,rpm,ipk" and convenient update filters. It also introduces a Windows EXE target, IPK/Listaller packages, support for PHP Phar archives, Composer bundle to system conversion, and a SRC input filter (for self-contained packaging info in scripting languages). "xpm" is
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.