I find that quite often the best and most useful information is not written down, but passed on by word of mouth. With the advent of podcasts it would of course be good to be able to search through those too. Well, Podzinger does just that. With some voice recognition technology, you can search in their database of audio (and video) and the results show how far into the media the word you're looking for turns up!
Google's missing a trick here. Though having bought up several companies recently (namely Adscape and Trendalyzer) maybe they'll target them for purchase too?