The NetBSD Packages Collection (pkgsrc) is a framework for building third-party software on NetBSD and other Unix-like systems, currently containing over 6400 packages. It is used to enable freely available software to be configured and built easily on supported platforms.
The MirPorts Framework provides a generic way to install third-party software on Unix®-ish systems (the closer to BSD, the better).
Currently supported are: MirOS BSD – https://www.ohloh.net/projects/mirbsd/ – primary OS, MidnightBSD – https://www.ohloh.net/projects/mnbsd, OpenBSD, Mac OSX
... [More] (somewhat), Interix (actually better than Mac OSX in some respects, but lacking interest) [Less]
The NT POSIX C Runtime Library is an IEEE standard runtime library for the NT POSIX subsystem. It can be used as a complete replacement or a side by side alternative for what is shipped with the Interix SDK.