Blogs allow for individuals to write articles for the internet.
A blog for a privte group of friends, where each one can have the administrative power to write a post. This allows for a group of friends to keep in contact with each other that is more direct then mass e-mails. They can all post comments and reply to others posts very easily. it can be closed to a few group of people or can be on the open web for all to see.
Oh wait, never mind. You could already do this on LiveJournal as recently as eleven years ago.
Instead of having Trained reliable writers to write articles for Top online sites or have casual individuals write for there own blog, a Guest blog could be created where no one in particular writes articles, but rather readers alike contribute to write articles for the blog. The blog may be about a particluar topic, but the readers combine together to create the content for the blog. Think Youtube meet's Blogshere. The readers make the content and the content attracts the readers.
A Very Specific Blog topic could be written about to Specialize on one particular topic. The blog may not have regular readers but could be seen as a reliable source of information and a good story that may be relatable. For example a blog about a person trying to get rid of athletes foot and there journey through there attempts to get rid of it. As they are attempting to cure them selves of the foot disease they can revel some research they may have come across while trying to get rid of there ailment. Unlike most blogs, once the problem is solved and the topic is exhausted, the blog comes to an end. There can be a link to a new blog or other web site, but the original Specific blog is left for all the web to enjoy.