This plugin generates dummy posts and dummy categories on WordPress. It will also let you specify a Blog Name and a Tagline to be set.
When I was developing blog themes, I found it useful to have a plugin generate a set of predefined categories and subcategories, and create random posts in them. It got tiresome making these by hand over and over, so I wrote a plugin that will do it. It will let you specify a post category hierarchy and other settings. These settings can be exported and applied on other blogs as well.