I had the opportunity to spend time trying out Crossover Mac. Crossover Mac is a program for Intel based Macs to run Windows applications without having to install Windows. Crossover uses the open-source project WINE to accomplish this. They have an impressive list of compatible applications such as Office 2003, IE 6, IE 7, Quicken, Visio, Half-Life, etc.
The concept is impressive, but I suppose I was expecting a little bit better from what people have been hyping. It is still clearly in the beta stages. The stability of the applications are questionable (since not all of Microsoft's APIs are accounted for) and the overall look and feel of the applications are not that great. I do realize that this is a huge effort trying to emulate the huge library of frameworks available in Windows without using Windows. Though, for any of these programs to be useful to me requires them to be responsive and stable. I can turn to Parallels for better compatibility and a more predictable operation (though it does require a license of Windows which is a drawback).
Crossover still has a long ways to go before I can use it every day. I can't wait for the day I can run Windows applications beside other Mac applications as seamlessly as Mac OS 9 applications ran in OS X with Classic.