I understand that blogspot addresses are not the best for marketing but I use blogger currently and have the blogs themselves hosted on the main domain.
the thing is you need a blogger blog to comment on a blogger blog, an msn blog to comment on msn news and it looks like the Yahoo! blog requires you to have one of your own as well. Therefor I have at least one of each while my search engine blog is the main one they all lead to.
I'm currently using a blog from www.modblog.com This is one of the easiest blog to use which I've come accross to date. It's very easy to change the layout and templates to your liking.
I just signed up for a blog with Opera as well, trying them all, I think the journal thing is it, right? http://my.opera.com/SiteTutor/journal
Wordpress kicks ass!! ... but you have to host it on your own domain. Just launched my first proper blog (see recent blog!)
You can start a free blog at www.Squarespace.com They also offer a free 30 day trial on the professional package with full features and automatic syndication of all content on journals. If you like what you build you can choose a plan at the end of the 30 day free trial or if you choose not to pay for a plan the account reverts to the free blog program by default. I have a couple with them that you can see at: www.webcenter.squarespace.com www.searchwars.squarespace.com You can use your own domain if you wish, you do not have to use the Squarespace domain.
IlohaBlog For free service I like IlohaBlog. I prefer Wordpress, but I don't know of a free service that uses WordPress.