Currently tracking 19 million sites and 1.5 billion links.
Technorati is the authority on what's going on in the world of weblogs.
What is a weblog? A weblog, or blog, is a personal journal on the web. Weblogs express as many different subjects and opinions as there are people writing them. Some blogs are highly influential and have enormous readership while others are primarily intended for a close circle of family and friends.