Firefox: Despite the popularity of Internet Explorer-alternatives there are still websites that are optimised for or outright restricted to Internet Explorer. Don't switch browsers, render IE-only pages in Firefox with this handy extension.
Coral IE Tab is a souped up version of the regular IE Tab extension you may already be familiar with. Coral IE Tab covers the basics: web pages you load with it are rendered to function and appear as they would in Internet Explorer.
It also adds in several handy features. You can now save cookies within your virtual Internet Explorer session so cookie-based information can be preserved between browsing sessions. Coral IE Tab also sports integration with AdBlock Plus—just because you're forced into the world of Internet Explorer doesn't mean you have to brave a world with blinking ads. Coral IE Tab also supports site-based preferences so you can flag pages that require IE, alternately you can allow Coral IE Tab to load automatically for any site that requires Internet Explorer.
Have you own method for dealing with IE-only sites? Let's hear about it in the comments. Coral IE Tab is a free Firefox extension and works wherever Firefox does.