Bernhard Kau

To be able to use the plugin, you have to get API credentials from Mailchimp. You can find them in the <a href="https://us1.admin.mailchimp.com/account/api/" rel="nofollow ugc">API keys section</a> of your Mailchimp account. If you already use the plugin “Mailchimp” or “Mailchimp for WooCommerce”, the API key from these will automatically be used.
The plugin allows you to show all campaigns from the connected Mailchimp account. You can show up to 100 campaigns (this is a hard limit of the Mailchimp marketing API). For each campaign, you can either show the “Title” or the “Subject”. You can also show the author/sender as well as the sending date (and time).
This is not an official Mailchimp plugin. Mailchimp® is <a href="https://mailchimp.com/legal/copyright/" rel="nofollow ugc">a registered trademark</a> of The Rocket Science Group.

Campaign Archive Block for Mailchimp

Adds a block to show an archive for Mailchimp campaigns.

tomotomobile

WP Campaign Manager, it is possible to simply add a shortcode to display the campaign banners while posts. Possible to manage the campaign on the dashboard. Super useful.
<a href="http://tomotomosnippet.blogspot.jp/2013/12/wp-campaign-manager-wpacja2013.html" rel="nofollow ugc">日本語の説明</a>
Header image created by <a href="https://twitter.com/luchino__" rel="nofollow ugc">@luchino__</a>
<h4>Usage</h4>
Easy to use it!
<ol>
<li>‘Add new’ and save.</li>
<li>Copy a shortcode. e.g. [wcm-show id=1111]</li>
<li>Edit your post, paste it, save.</li>
</ol>

WP Campaign Manager

Provides Shortcodes to display and manage your Campaign banners. Useful!

Campaign Archive Block for Mailchimp vs WP Campaign Manager