thewebist

This plugin provides the template tag <code>wp_get_post_image()</code>. Use it to call dynamically created images uploaded via the WordPress media uploader.
NOTE: This plugin is intended for use by WordPress developers and theme builders only.
<h4>Usage</h4>
<pre><code><?php wp_get_post_image($args); ?>
</code></pre>
<h4>Default Usage</h4>
<pre><code><?php $args = array(
 'width' => null,
 'height' => null,
 'css' => '',
 'parent_id' => '',
 'post_id' => '',
 'filename' => '',
 'return_html' => true 
); ?>
</code></pre>
By default, the function returns:
<ul>
<li>The last uploaded image wrapped in an image tag (<code><img /></code>).</li>
<li>A proportionately sized image with a <code>width</code> no greater than <code>200px</code>.</li>
<li>The CSS class <code>wp-image-*ID*</code> and no other classes.</li>
<li>If you add <code>thickbox</code> via <code>css</code>, the appropriate anchor <code><a></code> tag will be added for Thickbox compatibility.</li>
</ul>
<h4>Parameters</h4>
<ul>
<li>
width (integer) – Width of image.
</li>
<li>
height (integer) – Height of image.
</li>
<li>
parent_id (integer) – The ID of the <code>post_parent</code> for the attachment. Specifying the <code>parent_id</code> returns the first image attached to the parent post according to <code>menu_order</code>.
</li>
<li>
post_id (integer) – The ID of the attachment.
</li>
<li>
filename (string) – The filename that corresponds to the <code>post_name</code> of the attachment.
</li>
<li>
return_html (boolean) – <code>true</code> returns the image wrapped in an XHTML image tag. <code>false</code> returns the image’s URL.
</li>
</ul>
<h4>Example</h4>
<pre><code><?php 
// use this example wherever you have access to $post->ID, e.g. the WordPress loop
if(function_exists('wp_get_post_image'))
 echo wp_get_post_image('width=450&css=alignleft&parent_id='.$post->ID); 
?>
</code></pre>

WP Get Post Image

Adds the function wp_get_post_image(), giving theme builders easy access to images associated with a post or page.

ilonapetrak

Auto Attach Thumbnails is a plugin to set post thumbnail from first image in post. It requires to have attached/uploaded at least one image to the post. If there’s not any image attached to the post, thumbnail won’t be generated. If the post thumbnail is already present, the plugin will do nothing.
This plugin adds the feature image ID to your post(just the same that WordPress does when you set it manually). It does not remove anything after deactivation.
Auto Attach Thumbnails also provides a capability to chose posts for generating thumbnails from the list of posts without thumbnails. A new menu item Auto Attach Thumbnails will get added under Tools menu after this plugin is installed.

Auto Attach Thumbnails

Plugin did what it promised. First image in the post becomes featured thumbnail!

Excellent plugin

Automatically sets the Post Thumbnail from the first image uploaded into the post only if Post Thumbnail is not set.

WP Get Post Image vs Auto Attach Thumbnails