This is a great plugin that allows you to put posts onto a page to create a blog within a blog. There are other plugins like that, such as Aral Balkan's Inline Posts BUT the Composite Post plugin does something many, many people have ask for in Inline Posts and never got: Functionality of the more tag.
I've wasted a lot of hours trying various things suggested but couldn't get it in Inline Posts to work because I don't know PHP well enough to do more than ticker around things a little. Composite Posts lets you use
<!--more--> without problem!