Source URLs are awesome little 'meta comments' that the browser can use for finding the names of scripts. For example:

//@ sourceURL=my/script/name

This means that instead of seeing one compiled file in Chrome's inspector, like this:

You see your whole directory tree:

So much easier to navigate! The alternative to this is to spit out multiple script tags into the page.

Just require sprockets/source_url in development.

Both Chrome and Firefox have @sourceURL support. For more information, please see this excellent post on the subject.