WordPress Guest Post plugin by Lisa Angelettie is a simple plugin that allows you to accept, edit, & publish guest posts to your blog without writers having to login to your WordPress Admin area.
Easily obtain guest posts without user registration.
Users can add their posts right from a form hosted on a page on your blog. No logging in your WordPress admin.
Effortlessly manage and edit post submissions
Customizable post submission notification on site and via email
NOTE: this plugin is still in beta.
Plugin homepage: http://WordpressGuestPost.com