Software virtualization is a piece of technology that allows the running of applications, without having to install these in the "traditional" way.
Disk2vhd is a utility that creates VHD (Virtual Hard Disk - Microsoft’s Virtual Machine disk format) versions of physical disks for use in Microsoft Virtual PC or Microsoft Hyper-V virtual machines
CodeWeavers CrossOver Mac allows you to install many popular Windows applications and games on your Intel OS X Mac.
PearPC - PowerPC Architecture Emulator is an architecture-independent PowerPC platform emulator capable of running most PowerPC operating systems.
Vmdk2Vhd is a simple utility to convert virtual hard drive images from VMWare's VMDK format into the Microsoft's VHD format.
Virtual PC 2007 SP1 is a powerful software virtualization solution that allows you to run multiple PC-based operating systems simultaneously on one workstation, providing a safety net
Parallels Desktop for Mac is the first solution for Intel-Macs that give you the flexibility of running Windows or Linux on a Mac simultaneously without rebooting.