Tellini has released Quick Sprites 1.1 (http://www.tellini.org/mac/quicksprites/) on the Mac App Store. Found in the Productivity category, it requires Mac OS X 10.6.6 or higher and costs US$8.99.
Quick Sprites is designed to simplify the creation and maintenance of CSS sprite sheets that enable you to optimize your websites. CSS sprites help reduce the number of HTTP requests that the browser needs to do to load and render a web page. Quick Sprites automatically packs your images so that the resulting sprite sheet uses the smallest possible area, according to the folks at Tellini. Quick Sprites can also further optimize the resulting image, saving extra bandwidth, they add.