If you run WordPress as a CMS or if your site consists primarily of Pages, there's a chance you might want your blog to look quite different from
With this plugin you can set a base name for your blog pages. For example: http://www.yoursite.com/blog/name-of-my-post , where "blog" is the base for your blog pages. If the plugin detects the base name in the URL, it switches the theme to a completely different theme which you can select.
Similarly, in the WP Admin, while adding a new post, the theme is switched to the blog theme and it shows the blog theme's options instead of the default theme's options.
Read the installation instructions carefully before using!