An implementation of the Ext2 (Linux) filesystem for Mac OS X.
BSDStep is an open source BSD based distribution using code from the L4 Microkernel, DragonFly BSD, Cairo and GNUstep projects.
Crosos is a SubLinux Distribution
Crosos is a open-source OS. It is based on the Linux Kernel and mostly uses the same code in Ubuntu (but it has been derived from Debian)
DoubleCommand is a Mac OS X kernel extension that allows you to map keys on your keyboard to the way you want them.
Operation system FreaxOS
Labyrinth BSD is a stable BSD implementation intended for the average user.