It's already possible to filter out certain words, but not for a specific search -- you set it up in Options to exclude stuff (e.g. if you're looking for porn, you probably want to filter out any results that claim to be "illegal", "preteen", etc. -- yuk) ... also, it's my understanding (and observation) that Gnutella queries do match on shared subdirectory names. If someone's sharing a file named shared/foo/bar.mp3, a search for "foo mp3" will generally turn it up. I think it also matches metadata sometimes -- title info in a file for example. I've had a jpeg with a bogus-looking alphanumeric code turn up as a search hit, which when downloaded proved to be relevant, and had metadata (e.g. camera model, date picture taken, title) containing the search term.