I use WordPress as my blogging tool of choice. So do a lot of other people. If you’re more than a casual writer (at least in your own mind), then dump Blogger or whatever you’re using. Once you’ve tried WordPress you’ll never go back. Webmonkey agrees and has a nice introductury tutorial for you to read.
The best thing about WordPress (apart from it being free) is that plug-ins are available to do all manner of things, from inserting tag clouds into your blog to adding surveys and shopping carts to integrating YouTube videos. Not to mention the fact that you have serious control over the design of each section of your site.
WordPress is absolutely free and in the year or so I’ve been using it, has become a significantly more robust weblogging tool.