Simple Menu Search is just as easy as it can be. If you don't need it - you don't see it. If you need it - it's there.
When you are working or something like that, just hit a shortcut on your keyboard, type in what you want to search in the web (google, bing, yahoo or wikipedia) and a new browser window opens with the result.
NOTE: Simple Menu Search can only be purchased via the Mac App Store (the buy link redirects you to its App Store page). To purchase/download applications via the App Store an Apple account is required.