Remove core and contrib. modules css files I would like to prevent several contributed modules from using their own css files. Constantly having to reset their css and then apply your own is a waste of bandwidth IMO.

I tried this out with nice_menus and it didn't seem to do anything. 

Placed in template.php

    function phptemplate_variables($hook, $vars) {
        $css = drupal_add_css();

        $rm[] = drupal_get_path('module','nice_menus').'/nice_menus.css';
        $rm[] = drupal_get_path('module','nice_menus').'/nice_menus_default.css';

        foreach ($rm as $key =&gt; $value) {
            unset($css['all']['module'][$value]);
        }

        $vars['styles'] = drupal_get_css($css);
    }
I think the function should be named MYTHEME_preprocess_page.  Though a more common method is to add

stylesheets[all][] = nice_menus.css


to your theme's .info file.  nice_menus.css will be replaced by the one provided by your theme, or suppressed entirely if your theme doesn't contain this file.