Matt Swain has written a Safari extension called KeySearch that adds a new way of searching the Internet to Apple’s web browser. It uses short keywords to allow you to search any site you want from the toolbar.
So you might type “map New York to LA” to search Google maps, or “wiki mac os x” to search Wikipedia. It comes with a selection of ready-made keywords, and you can add your own for any search engine you want. You can check it out at http://www.macosxtips.co.uk/keysearch/ .