WordPress.org

This plugin gives you the ability to add a Author introduction to each post. No editing of themes is required to use the plugin and a default layout is set up on install. Play with the html layout until you get exactly what you want. A number of tags are provided to give you access to the Author data [authorID], [authorDisplayName], [authoremail], [authorURL], [authorPostsLink], [authorGravatar] and [authorBio] also optionally you can use php if you are an advanced user.

Tags are evaluated first, then php before the results are returned.

For more detailed information and installation information please visit this plugins home page