IEs4Linux is the simpler way to have Microsoft Internet Explorer running on Linux
IETester is a free WebBrowser that allows you to have the rendering and javascript engines of IE8 beta 1, IE7 IE 6 and IE5.5 on Vista and XP, as well as the installed IE in the same process.
How to get IE 5.0, IE 5.5, IE 6.0 and IE 7.0 (release) running concurrently on Linux.
Automated installation of the Microsoft IE App Compat virtual machines (virtualbox)
Microsoft provides virtual machine disk images to facilitate website testing in multiple versions of IE, regardless of the host operating system. Unfortunately, setting these virtual machines up without Microsoft's VirtualPC can be extremely difficult. The ievms scripts aim to facilitate that process using VirtualBox on Linux or OS X. With a single command, you can have IE7, IE8 and IE9 running in separate virtual machines.