CrossOver is an emulation layer for MacOS X and Linux. In contrast to virtualization solutions like VMWare, Parallels or VirtualBox, it allows running thousands of Windows applications, tools and games without having to install a legit Windows operating system.
Crossover allows installing Microsoft Windows based software on MacOS X or on Linux. In contrast to virtualization techniques like VMWare or Parallels, Crossover hooks API calls and redirects them to their MacOS or Linux equipollent.
As of version 8.0 these new applications are supported:
Microsoft Internet Explorer 7
Adobe Photoshop CS2
Crossover also improved Copy and Paste functionality to and from the host operating system and improved integration with the upcoming Apple Mac OS X Snow Leopard.