For those of you who love to run firefox but have to work in environments where you are developing for IE, don’t fret. The IE Tab plugin is a great way for you to have your cake and eat it too. After installing this plugin you can open a new tab using CTRL-T and navigate to a site (okay so far nothing is new). Let's say that the site can only render/function correctly is IE (Microsoft Update for example). If I know this, I can right click on the tab and get access to a new context menu item:

If I switch the rendering engine. The new tab will now use IE to render the page!! No more switching between firefox and IE!! Better yet, instead of having to manually switch rendering engines everytime I visit an IE only site. I can change the options for the IE Tab plugin and give it a list of pages that should always render using IE if visited. If I open a new tab and navigate to one of these IE only sites, firefox will automatically switch the rendering engine for me!