WordPress comes with an automatic update function through pingomatic. This service notifies a number of blog watchservices whenever you create or update posts on your site. You can turn this service off and on in the “writing” settings of your WordPress installation.
Technorati is probably the most well known blog watch service. It is rather like a search engine in that it looks at your blog and looks for what other blogs have linked to your site. It uses that information to rate blogs. There are a number of other blog directories, but I’ll single out Technorati for a closer look at why you’d want to use a blog watch service.
One of the main uses to Technorati is to determine how your site is doing in terms of inbound links. This is one important measure of how authoritative your blog is thought to be in its field. If credibility is important to you, it is a good idea to watch this measure. Of course, the inbound links will also bring traffic to your site so, it is always a good idea to try to increase them.
Technorati is also a research tool. You can find out who else is talking about whatever interests you, what they are saying and how much ‘buzz’ they have created. There really is a network of blogs out there and it a conversation can go on among bloggers. It can be useful if you read other blogs, quote them and link to them. This tends to be reciprocated. Allen Stern talks about these uses of Technorati in his lucid article on Center Networks. I also like Gina Chen’s article on why you should use Technorati.