I’ve been looking for a good live CSS reloader and the Auto Reload extension for Firefox is the best one I’ve found.

• It doesn’t require any programs or services running outside of the browser, so it’s more self-contained, and doesn’t break when you proxy your outbound traffic or use remote sandboxes.
• You can use a regular expression for to determine the URL that each rule applies to, which is extremely useful for WordPress Multisite installations.
• You can configure it to reload the entire page when PHP and JavaScript files change, but only reload the CSS files when they change.

The only problem I’ve had so far is that individual rules can’t override the global delay setting —  I want to set it to 10ms for sites on my local virtual machine, and a second or two for sites on my remote sandboxes.