What was going to be a search add-on for Safari is now available as a beta website. Combines instant search, suggestions and supposedly multiple search engines though right now that just appears to be links to elsewhere, not actually merged in the results. Uses google right now, which is not surprising since they already had a instant search interface.
I’ve seen various trials in libraryland for similar “instant searches”. This one has a nice merged interface. Perhaps we’ll have spellchecking and thesaurus instantly in the future. If you haven’t seen these “instant searches” before, do a search for ‘livesearch’ to see some examples and code for it.