Web logs, online diaries written and published by everyone from college students to big media companies, are being created and updated at an astonishing rate -- and established search companies such as Google Inc. and Yahoo Inc. don't always catch them fast enough. Now, a handful of closely held upstarts such as Technorati Inc., Feedster Inc. and IceRocket.com LLC see an opportunity: Build a search engine that can track the information zipping through blogs, nearly in real time.