WPCustomAds enables you to inject customized ads into pre-defined areas of your template. Similar plugins are way too hard to grasp as the end-user, which is something this plugin should be better at doing.

<h3>Arbitrary section</h3>
Use this wisely.

WPCustomAds

WPCustomAds enables you to inject customized ads into pre-defined areas of your template, using DOM-identifiers…

twapaw

Opes WP Ads Manager is a simple plugin that allows you to show advertisements as a widget on the website
 Just works! 
Major features in Opes WP Ads Manager include:
<ul>
<li>Since version 1.2.0 only one widget can be add and only two ads can be shown</li>
<li>An ad as a custom post type</li>
<li>An every ad can link to specific web page</li>
<li>A widget generator</li>
<li>A custom post featured image used as an ad</li>
<li>Ad sizes management (use Regenerate Thumbnails plugin to extend management of the sizes image files)</li>
</ul>
PRO Version (available soon) features:
<ul>
<li>Stats</li>
<li>Not limited widgets and ads can be add</li>
<li>Management of order of ads in a widget</li>
</ul>

Opes WP Ads Manager

Opes WP Ads Manager allows you to show advertisements on the website

WPCustomAds vs Opes WP Ads Manager