Technorati is a fantastic tool – but I'm not sure how well all of the features of it are really marketed. One of the features that I like is the ability to search all blogs for certain tags. I even subscribe to some searches.
Go to http://www.technorati.com/tag and you can find the top tags this hour OR you can enter some search terms. The resulting URL will look like this: http://www.technorati.com/posts/tag/adobe+apollo (if searching for adobe apollo).
If you notice, you can actually subscribe to that RSS feed now! Using a feed reader like Google Reader, you can get the most up to date blog entries on “Adobe Apollo” or whatever topic you'd when they are posted! It's kind of like setting up an alert for the entire blogosphere.
An alternative use for this is to search for a topic prior to blogging about it. This can provide your content with some robust references and trackbacks!