Firefox is by far the best browser I have used, and you no doubt agree, or you wouldn't be here. But some sites that I frequent just don't work in Firefox. (Most of those are hosted out of Redmond, WA.) I found myself having to copy a link, open IE, and paste the link in order to get to these sites. A thousand or so repetitions of this process was enough motivation for me to write a browser extension as a shortcut.
HOW IT WORKS:
1) If you right-click on a link, you will see the option "Open Link in IE"
2) Click the toolbar button to open the current page in IE
3) Press Ctrl+Shift+I to open the current page in IE