If you use Mac OS X, you're probably familiar with Spotlight, which searches your hard drive and displays results as you type. Well, why not bring that same capability to web searching? Inquisitor is a free OS X app that adds "search as you type" functionality to Safari. Install Inquisitor, restart Safari, and when you start typing in Safari's search bar, Inquisitor will display up to three links and several suggested keywords as you go.

This, of course, works best if you have a fast computer and fast Internet connection. I found Inquisitor to be a bit slow on my 800mhz iBook G4 (hey, we can't all have the latest and greatest). And of course, it would be simply impractical for Inquisitor to search the entire web as you type; instead it pulls its results from Google, Amazon, Wikipedia, and several other sources.

If you don't have Safari, there's also a free web-based version, currently in beta. I actually found the web-based version to be faster than the Safari version.