VMware Fusion is a virtualization program that lets you run Windows applications on any Intel-based Mac--and quickly switch back and forth between Windows and Mac apps. This app's Unity feature alone makes it worth trying VMware Fusion's 30-day trial. With Unity, Windows apps appear right alongside Mac apps as windows in your Mac OS, as well as in the Dock and Exposé. You can also get to your Windows apps directly from the Apple Menu bar, even when VMware Fusion isn't running. You can also set your preferences so that your Mac and Windows apps use the same user data (your Documents, Music, Pictures, etc.), and it interacts well with most printers and multiple monitors.
This version has made great strides at boosting speed and performance, with faster start-up and launch times, and it brings full support for Snow Leopard and Windows 7. This update also lets you take better advantage of both multiple processors and greater Windows graphical power, with support for Windows Aero and Flip 3D animations, and it's easier than ever to migrate a physical PC (or a Boot Camp partition or other virtualization app) to a virtual machine on your Mac. You can also use VMware Fusion to run Ubuntu or over 140 other supported operating systems. Still just under $80--with a free year of McAfee anti-virus and a year and a half of e-mail support--this is one of the cheapest ways to "buy" an easy-to-use Windows box. (And all without cluttering up your desk with ugly, non-Apple hardware.)