Internet Explorer 8 added a concept known as IE "Accelerators" - the principle being that you could select some text on a page, and using an accelerator, quickly search the web for that piece of text, or maybe do something more specific. The other day, I was talking to someone about a particular piece of kit, and we were looking at a website commenting on it. Looking for more info, I used one of the IE Accelerators to quickly Search with Bing, and he said, "wow - I didn't know you could do that..?!"
There are a bunch of Accelerators built in with IE9 - the most obvious ones letting you select something on the page and immediately search Bing for the text you've selected. Even handier, select a post code or place name and Map with Bing to view the map straight away, all without need to re-key everything.
There are other accelerators available - if you've got more than one Search provider (other search engines, apparently, are available) then they'll show up in the "All Accelerators->" flyout menu, and under the Manage Accelerators option on the same menu, you can find more or deal with the ones you currently have.
Check out the IE Gallery for more accelerators and other addons.