barteled

Slideshow background adds a full size, smooth transition slideshow to the background of a WordPress site. Images can be selected from the media library or uploaded via drag-and-drop. Every page load will begin at a random position in the image loop so that users are not presented with the same start image every page change.
Additionally, the images maintain their aspects ratios during resize and turn off for mobile users.
This plug-in was conjured up by a nerd at <a href="http://think-bowl.com/" title="It's less of a tank and more of a bowl." rel="nofollow ugc">Think Bowl</a>

Simple Slideshow Background

Display a full size slideshow in the background featuring images from the media library.

Chris Marslender

envoke

Dillon McCallum

This plugin creates an easy to use interface for managing the Supersized jQuery Plugin on your WordPress site. You have 
the option to define a global set of images as well as set up an image, title, and caption on a per post basis. The per 
post images will override the global images if set for a particular post.
Find a bug or have suggestions for improvment? You can contact us through our website 
<a href="http://envokedesign.com/" title="Web Design Portland" rel="nofollow ugc">Envoke Design</a> or create an issue using our 
<a href="https://bitbucket.org/envokedesign/envoke-supersized/issues" rel="nofollow ugc">Issue Tracker</a>

Envoke Supersized

This plugin creates an easy to use interface for managing the Supersized jQuery Plugin on your site.

Simple Slideshow Background vs Envoke Supersized