CrossOver!

Parallels Desktop gives Mac users the ability to run Windows, Linux or any other operating system and their critical applications at the same time as Mac OS X on any Intel-powered Mac Pro, iMac, Mac Mini, MacBook or MacBook Pro.

Lutris is an open source gaming platform for GNU/Linux. It allows you to gather and manage (install, configure and launch) all your games acquired from any source, in a single interface.

Wineskin is a tool used to make ports of Windows software to Mac OS X. The ports are in the form of normal Mac application bundle wrappers. It works like a wrapper around the Windows software, and you can share just the wrappers if you choose.Best of all, its free! Make ports/wrappers to share with others, make ports of your own open source, free, or commercial software, or just make a port for yourself! Why install and use Windows if you don’t need to?

Q4Wine is a qt4 GUI for wine that will help you manage wine prefixes and installed applications

WineBottler is an App to manage and wrap your Windows apps into convenient OS X apps. WineBottler helps you with running Windows programs on OS X.

Using Wineskin technology, Porting Kit is a PaulTheTall.com app that can install games and apps compiled for Microsoft Windows® in Mac OS X. It has access to a server where we store WSI files for more than 300 games, which can be installed by any Porting Kit user.

Vineyard is a collection of tools and libraries designed to make managing Windows programs on Linux easier. More specifically, it aims to improve the integration of Wine and the Free Desktop and to make it easier to create programs and tools that integrate with Wine.

Run your Windows applications on OSX without the need of buying a Windows license.Well, you even do not need to install Windows.Just download WinOnX and you are ready to go within 2 minutes.No need to install Windows or a virtual machine.