If you are currently in the market for a job, which I am, you may find that some companies and agencies will only allow you to access their online job application and job search system through Window’s Internet Explorer. I ran into this when trying to access the Texas Health and Human Services website. It would only allow access with IE 6.0 or later, it would not accept Firefox, Opera, or Safari.
For most people this would not be a big deal as many Mac owners also have a Windows computer somewhere in the house, I did not. What I ended up doing at first was using the Windows 7 beta in Boot Camp but that was a terrible solution for me as I did not really want to give up hard drive space for Windows and all of my information was already on the Mac side. Then I got some advice from the Live.Pirillo.com IRC chatroom about a program called IES4OSX, which is a workaround that will let you run Internet Explorer for Windows on a Macintosh computer.
The website to get it is here. It has full instructions on what to download and how to install it and once you are finished you have a working copy of IE6 that will run inside of OS X.
I tested it out on the Texas Health and Human Services website and had no problems browsing for and applying for jobs. I have not tried the browser on sites that require ActiveX controls but I seriously doubt they would work. The browser itself works fine although it does have some serious quirks in the graphics department, such as the address bar not showing your previously typed in web addresses, it tries to show them but it only shows about half of the first address. The scrolling function is also a bit mad, doing a normal scroll that might take you down a few inches in Safari or Firefox will suddenly have you rocketing towards the bottom of the page with no real way of stopping it.
Again, these are things that you can live with though as most people would use this program sparingly. It is bad enough that you wouldn’t use it on purpose for regular browsing, but when you need to access IE only sites, this is the only solution I have been able to find.