Chrome's default location bar behavior is the closest I've gotten to the mythical 'do what I want' in a browser. While there are extensions for Firefox that can mimic this, I instead have it set up to do something even more useful. When I know exactly what I want to find, I can specify what domain I want to search to get better results than letting the browser, or Google, figure it out.
For the uninitiated, the magic of keyword quick searches involves typing out a keyword - a few letters or a word - before your search query in the location bar. The keyword tells your browser which site's search you want to use. I'll run through how to set them up in Chrome, Firefox, and Opera, then offer some keywords that I use.