Aaron D. Campbell

Used to create a customizable rotating slideshow highlighting certain posts or 
pages. You can choose which posts or pages are featured by simply checking a 
checkbox on the write posts/page screen. The plugin uses the new post thumbnail 
functionality added in WordPress 2.9.
Requires PHP5.

Featured Content Showcase

Used to create a customizable rotating slideshow highlighting certain posts or pages.  Uses jQuery, which comes with WordPress (no conflicts).

maltpress

This plugin creates a widget which loops up to ten recent posts and cycles through them with your selected jQuery Cycle effect.
<h3>Settings</h3>
You can change the following settings:
<ul>
<li>Title: Widget title</li>
<li>Category: Category to draw posts from – the list is automatically populated. Make sure the category you want to use exists before you start! You can select any number of categories – use ctrl and/or shift to select more than one</li>
<li>Number of posts: Number of posts used – if there are fewer posts, that’s fine. It’ll just use the ones in your chosen category</li>
<li>Slider effect: jQuery Cycle effect to be used. To see a preview of all effects, check out <a href="http://jquery.malsup.com/cycle/browser.html" title="jQuery Cycle Effects Browser" rel="nofollow ugc">jQuery Cycle Effects Browser</a></li>
<li>Timeout: the amount of time each slide will show for, in milliseconds. For example 3000 = 3 seconds</li>
<li>Transition speed: how long it takes for each transition, again in milliseconds. For example, if you set this to 1000 it will take one second for a post to fade out and the next to fade in</li>
<li>Width: Add a width here if needed. By default, the widget should fit the sidebar you drop it in to. If not, you can override this by setting a width in pixels (don’t include the units, just the number)</li>
<li>Height: Set the height of the widget in pixels. Don’t include the units.</li>
</ul>
Add images to posts as follows:
<ul>
<li>Edit the post to add the image to</li>
<li>Add a custom field called “slider”</li>
<li>Use the path to an image for the custom field value. This can be one in your media library or use an absolute path from another site if you have permission to do so.</li>
<li>That’s very important – image leeching is naughty.</li>
<li>Update your post.</li>
</ul>

Scrollarama

Creates a loop of recent posts (up to 10) with images, within selected category, and scrolls through with jQuery effects

Featured Content Showcase vs Scrollarama