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.

aptivadadev

Login to your Audience Admin account to get your contest/promotion created. Choose one of our professionally designed templates (or start from scratch) and customize it to your liking. Audience’s plugin provides a shortcode to easily place your contest anywhere you like. When your contest or promotion is up and running, Audience will store all entry data: email addresses, photos, videos, votes and more. You can export your data at any time to use for future marketing efforts. Audience also provides in-depth analytics to help you understand where your “audience” is coming from.
Don’t have a Audience Admin account yet? Head to <a href="https://www.audience.io" rel="nofollow ugc">Audience.io</a> and request a demo.

Aptivada for WP

Easily add contests/promotions to your WordPress site using our plugin

Genesis Promotion Box vs Aptivada for WP