But there are other blog search engines, each of which has a particular strength, according to ReadWriteWeb writer Marshall Kirkpatrick. He's created a chart of that shows which to use for what. , for example, has an option that filters out posts from blogs that aren't widely linked, so your results won't be cluttered by spam-laden blogs that use content scraped from other sources. These "splogs" are designed to display ads to surfers who unwittingly click through to them from search engines.

Most important, Kirkpatrick found that no one search tool found every blog post on the Net. found posts that Technorati missed, and vice versa. If you're looking to find everything being said about a topic, you need to hit them all.