search_index hardcodes boosts to html elements. Should be configurable.

This code in search_index boosts various html elements in various ways:

  // Multipliers for scores of words inside certain HTML tags.
  // Note: 'a' must be included for link ranking to work.
  $tags = array('h1' => 25,
                'h2' => 18,
                'h3' => 15,
                'h4' => 12,
                'h5' => 9,
                'h6' => 6,
                'u' => 3,
                'b' => 3,
                'i' => 3,
                'strong' => 3,
                'em' => 3,
                'a' => 10);

The result is that the text in the title is 7x more important that text that is boldfaced. This might be fine, but the decision is arbitrary. Administrators should be able to tweak these decisions. The simplest solution would be to replace each of these values with a variable_get(). That way search admins could tweak the values in settings.php. A user interface could be built later, or could be built for admin/settings/search.

The ramification of changing these values is that they apply at index time. If you have some content indexed, and then you change the values, the next content you index will have the new weights applied but the old content will still be indexed with the old weights. This won't cripple search, but if you want the entire index to be uniform you'd need to reindex. Therefore a UI that offers admins the chance to tweak the weights should either automatically trigger a re-index or offer the advice that one should be triggered manually.