Link: http://technology.amis.nl/blog/4967/ietester-developtest-your-site-in-ie-6-7-and-8-rc1
by Emiel Paasschens
"When developing or testing your web application, you often have to support different browsers and versions. On Window machines testing for different versions of Firefox, Opera and Chrome is not a real problem as these browsers all allow you to install different versions on one machine. Only Internet Explorer (IE), is always a bit more difficult, because it’s integrated in the OS (Windows) of the machine. This mostly ends up installing multiple IE versions on multiple (virtual) machines, which is not a nice way of working when developing. Can we do this different and easier? Yes, we can!
The solution is quite easy and even easier then having multiple version of Firefox, Opera or Chrome on your machine.
How? Just try IETester. This is a free web browser that emulates IE5.5, IE 6, 7 and 8 RC1 in one browser. You can even open multiple IE 6, IE 7 and/or IE 8 tabs at the same time!"