Google and Yahoo! have conquered the vast majority of search zones, though I believe they have skipped two areas that I am constantly finding myself yearning to search; history and bookmarks.
So many times I've remembered a story that I've previously read or bookmarked and yet I can't find it because the details I'm looking for are not contained within the meta-data.
The new Mozilla Places functionality may be a good area to test this implementation. The Places Browser History seem like the most likely spot to hook in. Will this be extensible? Can keyword indexing be added through extensions or third party programs like Google Desktop?