A month ago, I wrote about my technique to output a CSS sprite for ASP.NET. Granted, I made a big mistake. I put WAY too much bloat into the post. Not a K.I.S.S. moment.
I have reworked my CSS sprite technique to be unique to MVC. I've used the most recent build of the MVC framework, which can be downloaded on Codeplex, to take advantage of ActionResult. What the ActionResult does is makes your controllers more testable and makes the execution of the controller more specific. Instead of a void, controllers now return an ActionResult (see Scott Guthrie's post on the interim release).
I have a download, see the bottom of the post, that includes a sample application and a class library that you can distribute with any MVC application. The sample pulls 2 images off the Internet, plugs them into a sprite through the Sprite controller.
What you get when you execute the Sprite controller is a sprite that looks like so:
What you do in your CSS file is reference the sprite URL and specify the background-position, width, and height.
Then with the following HTML:
you get the images separate from the sprite.
What you get is an easy-to-use API for sprite generation and faster-loading website (less HTTP requests per page) using sprites instead of multiple images. If you want all of the CSS editing to happen at runtime, see my original post of CSS Sprites for that code.