Desktop search engines seem to be the best thing since sliced bread, with Microsoft, Google and many other big players in on the game with their own products. These apps will find your files no matter where you stashed them, working just like an internet search engine to instantly pull up references to files based on keywords, file types, or designated folders. A great review here
has the low-down on six of the main contenders in this market, those being Blinkx, Copernic, Google Desktop (Beta), HotBot, Lookout and X1. There are links to fuller reviews of the products as well as a breakdown and comparison of key features.