Open Emu is an open source project to bring game emulation to OS X as a first class citizen, leveraging modern OS X technologies such as Cocoa, Core Animation and Quartz, and 3rd party libraries like Sparkle for auto-updating. Open Emu is based on a modular architecture, allowing for game-engine plugins, this means Open Emu can support a host of different emulation engines and back-ends while retaining a familiar OS X native front-end.

The goal of SkyEye is to provide an integrated simulation environment in Linux and Windows. SkyEye environment simulates typical Embedded Computer Systems (Now it supports a series ARM architecture based microprocessors and Blackfin DSP Processor). You can run some Embedded Operation System such as ARM Linux, uClinux, uc/OS-II (ucos-ii) etc. in SkyEye, and analysis or debug them at source level.

Run Windows, Linux and a lot more Systems on your Mac. Q is a feature packed cocoa port of QEMU: Switch fast between guest PCs. Save and restart guest PCs at any stage. Easily exchange Files between Host and Guest. Q makes use of OS X most advanced technologies like openGL, quartz and coreaudio to accelerate your experience with your guest PC.

QEMU is a generic and open source machine emulator and virtualizer. When used as a machine emulator, QEMU can run OSes and programs made for one machine (e.g. an ARM board) on a different machine (e.g. your own PC). By using dynamic translation, it achieves very good performances. When used as a virtualizer, QEMU achieves near native performances by executing the guest code directly on the host CPU. A host driver called the QEMU accelerator (also known as KQEMU) is needed in this case. The virtualizer mode requires that both the host and guest machine use x86 compatible processors.

Fuse (the Free Unix Spectrum Emulator) was originally, and somewhat unsurprisingly, a ZX Spectrum emulator for Unix. However, it has now also been ported to Mac OS X, which may or may not count as a Unix variant depending on your advocacy position. It has also been ported to Windows, AmigaOS and MorphOS, which are definitely not Unix variants.

innotek VirtualBox is a family of powerful x86 virtualization products for enterprise as well as home use. Not only is VirtualBox an extremely feature rich, high performance product for enterprise customers, it is also the only professional solution that is freely available as Open Source Software under the terms of the GNU General Public License (GPL)