code.google.com/p/bundle-fu - Rails Plugin for Bundling

Bundle-Fu is a RubyOnRails plugin for bundling together Javascript and CSS, so instead of having fifteen lines of code, you'll have a tidy two lines. Thus, you'll have less links to concern yourself with on your Rails enabled pages.

Using bundle-fu doesn't require a separate config file, there are no server restarts, nor will you have spend your precious time rewriting existing assets include code. Furthermore, Bundle-fu regenerates bundles as you modify files or change the include order, it puts bundles in javascripts/cache and stylesheets/cache, and rewrites relative URLs in your CSS files, so you won't have broken images. What Bundle-fu does not do is compress CSS or Javascript as the maker of the plugin—one Tim Harper, doesn't believe it enhances performance. The download is available under Google Code.