You're probably already aware of Google's instant search feature. http://www.google.com/instant/ This is a really neat idea of giving you results as you type, helping you key in on search terms or just save time. Unfortunately, it just doesn't seem to click with most people. I admit I have only begun to really feel some benefit. It doesn't help on every search, but when I can simply redefine my search before refreshing the page on a more niche query it does save me time. It also helps me get a better conceptual idea of the keyword web space.
I just learned about keyboard navigation on Google Instant, which I think might make this product even more useful for me. http://googleblog.blogspot.com/2010/09/fly-through-your-instant-search-results.html
A new instant feature from Google is now out though, one that I think could be more useful than either of the other projects similarly branded. Instant preview (http://googleblog.blogspot.com/2010/11/beyond-instant-results-instant-previews.html) gives a snapshot of the page in the search results, no need to go the page. A picture is worth a thousand words and this can easily help me skip the results I'm not interested in.
I do however wish they had made the snapshot show up automatically as you hover over the links by default, instead of having to turn it on the first time by clicking on the magnifying glass. Also, the need to actually perform the search (i.e. leave the instant search function) is also aggravating. Just show me a preview of the top result and let me use the arrow keys to exit and return to instant search without finalizing my search.