Creato

Simply upload your icons individually to your theme’s “images/csprite” folder.
Go to WordPress Dashboard > Tools > CSprite > Rebuild to rebuild the sprite.
CSprite will do all the hard work of combining all the images into a single graphic.
It will create all the classes for you in the enqueued stylesheet.
You can then simply use the sprite in your theme like this:
<div class="csprite csprite-creatomatic_logo"></div>
It will name the classes according to the image names, so make sure that they are unique.
Read more about this plugin at http://www.creatomatic.co.uk/csprite-automatic-image-sprite-tool-wordpress/

CSprite

The automatic image sprite generator for WordPress

NuWEB

Nusprite plugin allows you to generate sprite images from featured images of posts and get CSS rules with PHP.
<h3>Features</h3>
<ul>
<li>Choice in image source (feature image or custom field)</li>
<li>Versioning system for long term file caching</li>
</ul>
nusprite.pot file available

Nusprite

Sprite image generator. PHP methods are available in order to get positioning of each element and write CSS rules.

CSprite vs Nusprite