Ron Rennick

Uses a custom post type to allow editing of the promotion(s). The most recent published promotion post by date is shown below single posts.
Some (CSS tips)http://wpebooks.com/free-plugins/genesis-promotion-box/ for your child theme.
Requires the Genesis Theme Framework.

Genesis Promotion Box

This plugin allows you to add a promotion box after a single post in Genesis.

garo

Everytime you Publish a new post, this plugin will automatically 
send the update information to Pingler.com so the whole world can 
be notified that you keep your content fresh.

Pingler

This Plugin is used to automatically Ping new posts to a variety of online blogs. For use with Pingler.com

Genesis Promotion Box vs Pingler